How to build IR remote controls

This page explains how to build remote controls for military use that are immune to jammers.
And also explains how to build very fast high voltage ignition systems that can help hit fast moving vehicles.

Advantages of optical remote controls :
Immune to jammers, because unlike radio waves it's easy to shield away the light from unwanted directions.
Cheaper than any radio system.
Long shooting distance of up to 10 kilometers.
Can be made invisible to radar and immune to electromagnetic impulse weapons and EMP from nuclear weapons.


Receiver

IR remote control receiver

This receiver is intended  to be dug down, at a depth where it is invisible to airborne radar.
It has a built in voltage converter that stores 95 Volts in capacitors for faster ignition of the blasting cap.

Only non-metallic parts above the ground.
A plastic PMMA glass bar inside a black tube connects the light from the cone to the photodiode inside the box.

A red high power LED in series with a resistor is connected on the front of the box instead of a blasting cap, because this is only a test. And we want to find out how long is the maximum shooting distance.

The shooting range is an abandoned railroad.

Transmitter

IR remote control transmitter

 

 


 

 

IR remote control transmitter pcb
Transmitter printed circuit board.

 

IR remote control receiver pcb
Receiver.
This picture shows an alternative configuration in which the photodiode is external and above the ground level.
And there is a cable instead of a glass bar.

 

IR remote control receiver pcb
Receiver printed circuit board under test.
A BP104 photodiode to the right.

Very little leaking is measured from the high voltage circuit to the photodiode input.
But I recommend the use of a shielding plate between anyway.
This circuit must only be used inside an electric shielding metal box because it is too sensitive.

 


The high voltage transformer is built from an AM-radio ferrite rod antenna.
Two layers of 0.2mm diameter copper wire and then also a feedback coil.
This is a very high efficient voltage converter.

 


The delay time is measured from when connecting voltage to the transmitter circuit
till the receiver relay connects the 95 Volts to the blasting cap.
But this is a test circuit, and the real transmitter has 5.5 mS instead of 5.0 mS between each pulse.
Which means about 125 mS delay time instead of 115 mS.

 


Testing results :

The receiver's power consumption is about 8 mA at 5 Volts, which means that AAA size batteries will last about 225 hours.
But 4mA is lost in the LT431 voltage regulator which means that the circuit can be improved with small changes.
And the capacitors were bad types I found on the dump with high initial leaking current.. And it's not necessary to connect more capacitors than what is needed to ignite the blasting cap.
Connect more bigger batteries in parallel if you want extremely long standby time.

The delay time is 23 pulses instead of 19 as calculated, but the 6.8 uF +/- 20% capacitor is also measured to be bigger than average marking.
In combination with the biggest source of timing error, your own trigger finger (+/- 50mS) can you hit a fast moving vehicle with an accuracy of +/- 1.5 meters when moving at a speed of 70 km/h.

The charge-up time is not measured but is about a minute. The time it takes to charge up the capacitors to 95 Volts.

Maximum shooting distance is measured to be 235 meters  +/- 1%.

But this is a worst case configuration in which a glass bar is used, and a bad reflecting non-metallic cone, and a small 33.5 mm diameter transmitter lens.
And the shooting distance is about the double (470 meters) in configurations where the photodiode is connected directly to a high reflecting metallic cone with no glass bar between. And another doubling (940 meters) if a 65 mm diameter transmitter lens is used.
And I believe that we shall turn down the receiver's sensitivity a bit to make it more safe and less sensitive to disturbance and jammers.

The landscape is often polluted with metallic garbage which means that under normal conditions there is no need to use a non-metallic receiver because the enemy already have too many false alarms. (But a non-metallic optic fibre can be useful if the enemy uses EMP weapons to neutralize electronics.)

The blasting cap can be mounted inside the box if you want to shield it from EMP-weapons, and connect it to an explosives filled plastic tube through a cable gland.
A 5 - 10 meters long explosives filled plastic tube between the receiver and the non-metallic bomb under the road will make the bomb invisible to metal detectors.
Or as an alternative, use SIM-EFP at the roadside at a safe distance from the metal detectors, maybe of jump up type to hide the EFP from radar. The jump up mechanism can be built from gas-springs from a car door and door hinges.

 


IR remote control receiver circuit

Receiver :

Optimized for four alkaline batteries.
If you use any higher battery voltage then you must change the 270 Ohm resistor above.
Delay time of 110 mS  from when you push the transmitter trigger button till the relay connects the 95 Volts to the blasting cap.

Make sure to use a BC547C or similar high HFE type at the input stage because the amplification is only 50% if you use a low HFE type like BC547A. Which means about 30 percent shorter shooting distance.

 

The electrolytic capacitors give protection against ignition caused from glitches in the battery connection, but never trust anything for 100% and you will live a longer life. Always connect the battery before you connect the blasting cap.

The 2.2M resistor at the input is necessary when used in darkness.
Don't be fooled to remove it when you find out that the circuit works well without it, when testing in daylight.

Cheap and simple :
This receiver is a minimum construction, and the safety is good enough if you know what you are doing. But the safety can be improved further if you add more filters.

Notes :
The PCB has room for up to 4 * 1000 uF high voltage capacitors, but you should only install as many capacitors as is needed to ignite the blasting cap. This will save your money and also increase the lifetime of the batteries because of lower leaking current through the capacitors.

The intention of this webpage is to help you build remote controls from electronic parts easily available in an occupied nation.
The TL431 is a very cheap voltage regulator or programmable zenerdiode that is used to stabilize the high voltage and the delay time. It is used instead of a zenerdiode because all zenerdiodes below 6.2V are inaccurate piece of shit.
But the TL431 can be exchanged with diodes or a zenerdiode as long as you know what you are doing, and the voltage across the zenerdiode should be about 3.9 Volts.
The BAV21 (250V) diode can be exchanged with two 1N4148 (75V) in series.
If you can't find any high voltage transistor (50Volts) for the high voltage circuit, then try make the second layer of the high voltage transformer from thinner copper wire.

Use a 5Volt relay.

IMPORTANT NOTE !

You have to "burn-in" the receiver circuit's electrolytic capacitors before the first use.

Any new electrolytic capacitor that has been stored on the shelf for months will get the insulating Aluminum-oxide layer degraded, which means that the capacitor will leak too much electric current.

The receiver circuit on this webpage will not work properly until the insulating layer in the capacitor is built up again.
The restoration of the insulating layer is done by connecting the circuit to the battery voltage and wait for 5-60 minutes.

When you connect the circuit to the battery for the first time, there is no high voltage because the leakage current discharges the capacitor too fast.
But wait for 5-60 minutes and the voltage will slowly go up to about 95 volts, as the leakage current through the capacitor decreases.

Next time you connect the circuit to the battery, the voltage will go up to 95 volts in less than a minute.
Unless you have stored the circuit too long, and have to repeat the "burn-in".

Buy low leak capacitors.

 

 

 

How the receiver's sensitivity is affected by daylight-DC and sunshine-DC.

A typical photodiode  (LT536)  has a sensitivity of 42uA for 1mW/cm2
Which tell us nothing and we have to measure to se what it really means.
54uA DC measured at sunny daylight directed up in the sky.
269uA DC directed at the sun.

 

Input DC current Relative AC sensitivity Relative shooting distance
10uA 1 1
50uA Daylight 0.94 0.97
90uA 0.82 0.91
150uA 0.71 0.84
260uA  Sunshine 0.54 0.73
The shooting distance is decreased to 73 percent if the sun is shining into the photodiode.

It seems like no trouble when using 1-2 photodiodes in parallel.
But you need to shield away the sky light that causes too high DC current if using more photodiodes in parallel.

 

 

IR remote control transmitter circuit

Transmitter :

Current :  2 Ampere, 100uS pulse every 5.5 mS
You can change the electric current to fit your own LEDs by changing the 0.33 Ohm resistor.
No power resistor necessary because it's a short pulse.

You should put a lens or a simple magnifying glass in front of the LED to
increase the shooting distance 5 - 25 times. ( Read more below.)

The BDX33 transistor is of the darlington type. See datasheets on the web for more information.

The 47 Ohm resistor is for safety against unintended trigger, and discharges the 1000 uF capacitor in less than 0.25 seconds,  because the circuit will emit pulses of light until the capacitor is fully discharged, even if you don't push the button.
The 1000 uF capacitor is necessary as an energy reservoir because the battery itself can't deliver 2 Ampere current.
The resistor in parallel with the LED is against light caused from leaking electric current. It's about being invisible on the battlefield.

The battery's internal resistance together with the 2.2 Ohm resistor protects the switch against high current which else limits its length of life. This resistor is not necessary if used with a standard 9V alkaline battery which has a high internal resistance.

Connect to a tiny 9V alkaline.
This circuit is optimized for a 9 V alkaline battery.
A tiny 9V battery has the energy to blow up at least 15 000 vehicles.
Which means that the battery will last the entire war and you never have to change it.

LED Everlight IR383
From the datasheet :
  Maximum continuos current 50 mA
  Max 1A 100 uS pulse, dutycycle 1% ( means 10 mS pause between each  pulse)
  Wavelength 940 nm
  Output light power  900mW/Sr at 1 Ampere
  View angle 20

And you get 10 for a dollar.

The datasheets are always about recommended limits for eternal life, but we don't want any eternal life, and would rather barbecue the LED in a few minutes if it helps improving the shooting distance.
A few minutes means thousand exterminated enemy vehicles.

My own testing tells that the LED survives more than 2 Ampere electric current. (pulsed 100 uS, dutycycle 2%)
This will give 60 - 75%  more output power, and 30% longer shooting distance.
( 3 Ampere if you press the button only 0.6 seconds and then let it rest for a few seconds. )
This is near the edge, some LEDs may be destroyed early. Lower the current if you are a chicken.

If you use fast high voltage for the blasting caps in the receiver then can you try a "one-shot" timer circuit at perhaps 200 mS, and increase the current to the LED.

The LED has been tested to survive 7 Ampere for 5uS pulses, and 6 Ampere for 20 uS pulses, 9mS pause between every pulse. (Tested in 15 minutes of continuos barbecuing) But my own testing showed that most sources of disturbance and unintended trigger are easier to filter out if you use 100 uS pulses. It's about safety.


Mass-production of PCBs Printed Circuit Boards

ZIP-file of the transparent OH-sheet above in full size, 183 kB
Right click and save to your HD.
Unpacks as 5023 x 7104 pixel BMP-file of size 34 MB
One receiver on a 75*100 mm PCB.
Four transmitters on a 75*100 mm PCB.

Print out the circuit boards on a transparent OH sheet on any printer, for phototransfer to a circuit board.
If your printer is bad or dusty, then you must use two sheets on top of each other and use a fine-tip pen to fill in missing black.
You can buy circuit boards precoated with photoresist.
And You will save some big money if you buy an UV fluorescent tube and build your own UV equipment.

My own printer Canon IP4200 can print out photos but not OH borderless, and I had to resize the BMP minus 3 percent.
Use the attribute or exact size settings in MS Paint to resize. Do not use the resize function. This will add or remove white borders instead of replacing black with a mess of gray tones. (You can't use gray for phototransfers.)


Cheap homebuilt UV equipment.

Multiple UV-tubes, or move the UV-tube between multiple exposures.
That will spread out the ligth more uniformly.

 

 

You will need these chemicals. Buy at a paint-shop.

NaOH the same as used for cleaning sewage pipes.
10 grams per liter water.
Use it to develop the photoresist.

Hydrogen peroxide H2O2 of about 20 % concentration mixed with HCl and perhaps some water to slow down the reaction.. (If it stinks chlorine gas then you use too little H2O2, add more.)
Use it to etch the copper foil.

Ant then finally remove the remaining photoresist with high concentrated NaOH solution.

 

Top view of the receiver PCB

 

 

Top view of transmitter PCB


Safety

This little cable is your life insurance.


Solder the wire for improved safety.

 

And also remember that the photodiode must be 100 percent electrically shielded.
Use a shielded cable of high quality, and put the photodiode inside a metal construction that is connected to the shield.

 

Atmospheric disturbance :

The atmosphere acts like a lens when it is compressed and decompressed by the whirlwinds up in the sky. And with the sun at the other side it will create a modulated twinkling light that is too fast for your eyes to detect, but is measurable in the receiver.

The question is, how the safety is affected ?


Filter stage

Outdoor testing :
When tested with direct sunlight shining on the LT536 photodiode.
150mVpp (atmospheric disturbance) 500Hz peaks was measured after the 47nF capacitor.  20mV mean value.
And less than 4 mV after the 10 nF capacitor which gives a security factor of 9 from the trigger level of 36 mV.

When the sun was shielded away the peaks was at 10mVpp after the 47 nF capacitor.
And could not be measured (with an oscilloscope) after the 10nF capacitor.
Which means 15 times more safe.  (15 * 9 times from the trigger level)

Conclusion :
Don't let the sun shine into the photodiode, and you get 15 times more safety.

 

 

There is a risk of blowing your head off if increasing the receiver's sensitivity too much.

If you can't avoid the sun shining directly into the photodiode.
Then the following maximum shooting distances and corresponding sensitivity will give a safety factor of about 5 times.
150 meters for a 30 mm diameter transmitter lens
300 meters for a 60 mm diameter transmitter lens.
This is the sensitivity you get with a single photodiode in the receiver, and if you use no cones or lenses in the receiver.

But the suns path on the sky is predictable which means that you usually can avoid the direct sunlight, and then can you increase the sensitivity 15 times to get the same safety level.
Which in theory means 580 meters for a 30 mm diameter transmitter lens.
But I recommend to design for 300 meters and instead win more safety. Because all other handheld weapons on the battlefield have about 300 meters effective range.

A thumb rule of safety is to increase the transmitter's output power instead of increasing the receiver's sensitivity. You get four times more safety if you use a 60 mm diameter transmitter lens instead of a 30mm diameter lens, and design for 300 meters maximum shooting distance. But perhaps the transmitter becomes too big and bulky for your pocket.

You can win the most safety by limiting the photodiode's view angle, with a tube around the photodiode. If you limit the illuminated landscape area that the photodiode can see to 1 percent then it has become 100 times more safe. And the only thing the photodiode really must see is the transmitter's LED.

The safety can also be improved if you add more filters to the construction.
But the best is to use a more complicated tone modulated circuit and system, but it cost a bit more and takes more time to solder together. And the resistance perhaps prefer a system that has the best balance between safety, cost and time to build at home.

A tone modulated system compared to the impulse system above, can be made immune to atmospheric disturbance and other sources of twinkling light. It's more safe.

Another risk factor is oscillating plasma in lamps and mobile telephones and displays on watches.
Don't come near with torches or lamps.

As a thumb rule, the blasting cap is the last thing to connect, (or first thing to disconnect).

 




Theory

The rest of this page explains how to increase the shooting distance and safety.

 

The picture below explains why you should try to increase the transmitter's output power before trying to increase the receiver's sensitivity.

 

 

 

How to increase the shooting distance :

First of all :
The square law of attenuation for propagating light waves.

The measured voltage from the receiver's photodiode is attenuated with the square of the distance away from the transmitter.

At 2 meters the received voltage is 1 / 4 of  what you get at 1 meters.
At 3 meters the received voltage is 1 / 9 of  what you get at 1 meters.

You can use this square law to calculate the maximum shooting distance if you know the received voltage at a specific distance, and if you know the receiver's trigger level.

This is the thumb rule you have to learn :
Whatever you do to increase or decrease the received voltage N times means that you also have improved or sabotaged the shooting distance with SquareRoot(N)

 

How to increase the shooting distance :

1  Squeeze out the power from the LED

The LEDs output power is proportional to the electric current. The more current the more light and the longer the distance we can shoot from.

LEDs can be pulsed with 10 - 200 times more electric current than it can survive continuously.
(But there are some rare types of LED's that can't survive high current pulses.)
And you can find the answer in the manufacturers datasheets or by a destroying test.
The maximum electric current values in the datasheets are not to be taken seriously, because those values are the manufacturers recommendations for eternal life.
In this remote control application it is OK if the LED only survives a few minutes.

The shorter the current spikes, and the shorter time you press the button and the more time you let the LED cool down the more power you get.

Destroying test.
You can find out with a destroying test how much current a specific LED can take by measuring the emitted light. Too much current and too long pulses will at last destroy the LED, which you can detect as a drop in output power, and the light will become weaker.

A circuit for destroying test

 

 

2  Put a lens in front of the transmitter's LED.

A simple magnifying glass can focus the light from the LED in a smaller brighter spot. And you can reach targets 5 - 25 times more distant, dependent on the lens diameter.
The light spot on the right picture above is measured to have 100 times stronger light, which means 10 times longer shooting distance. ( This 100 times ratio is not visible to your eyes because your eyes have a logarithmic sensitivity scale.)

The disadvantage is that the light will be focused in a narrower beam which makes it necessary to also include a sight for aiming exactly at the target. Especially if you use invisible IR light.

You can temporarily exchange the IR-LED with a visible light LED when adjusting the sight.

The amplification is caused from the lens ability to focus the light like a cinema projector. The lens converts the divergent beams of light into parallel beams of light.

 

The increase in shooting distance is dependent on both the lens diameter and the LED's view angle (or half power angle from the datasheets).

Thumb rule
The increase in shooting distance = Lens diameter / LED diameter.
Except for narrow angle LEDs where only a tiny part of the lens i used.

These thumb rulez are only approximations because lenses are spherical approximations, and the LED's light intensity is not uniformly distributed. The light is strong in the middle and weak at the outer edge. And light power is always lost through reflections when passing through a lens. And the true increase in shooting distance is about 80 percent of calculated values.

 

 

The methods 3,4,5 below are the most safe and useful in combination with a tone modulated system.
There is a risk of making the receiver too sensitive if using the methods 3,4,5 below in combination with an impulse system.

 

3 Also put a lens in front of the receiver's photodiode.

If you put lenses in front of both the transmitter and the receiver, then you can reach targets up to 10 kilometers away.

Because if a single lens improves the distance 20 times, then a double lens system improves the distance 20 * 20  = 400 times.


A disadvantage is that the receiver becomes bigger in size and harder to hide.
And the aiming of the receiver becomes more complicated.
Because the receiver's view angle becomes very narrow.

In order to make the aiming of the receiver easier, only small thick lenses with a short burn width (short focusing distance) is used. This will give the receiver a wider view angle.

The amplification is caused from collecting the light from the entire lens area instead of only from the photodiode's sensitive area.  (Compare the area.)
The improvement in distance is sometimes as easy as :
   lens diameter / photodiode diameter

Or  SquareRoot( lens area / sensitive photodiode area )

 

Cut a 10mm diameter LED with a saw, clean and polish, and you have a very cheap lens that you can use.


A lens works well with all flat surface types of photodiodes.
But can be useless with photodiodes that already have a built in lens.

The lens above tested with different photodiodes :
Tested with a BP104 (flat surface, no built in  lens) the received voltage was improved 11.6 times. Which means 3.4 times longer shooting distance.
This tested lens has a view angle of about +/- 9.2 degrees if used together with a BP104 photodiode,  (proportional to the width of the 2.2x2.2mm sensitive chip area).
The BP104 itself has a +/- 60 degrees view angle when used without any lens.

Tested with BPW41N, the received voltage is improved 6.5 times, but the encapsulation of the photodiode is too thick to allow the use of the optimum short distance for the tested lens.
Tested with PD410PI (tiny built in lens), improvement 5 times
Tested with SFH 2030F (a LED-shaped with built in lens) it becomes dead, no received voltage at all.

 

The more sensitive you make the receiver the more sensitive it will become to lamps and jammers and atmospheric disturbance. And at last you will blow yourself up.
Therefore, try improve the transmitter's output power first of all.

You must shield away any direct sunlight from shining directly on the photodiode or else there is a risk of blowing your head off.

 

 

4 Put a cone in front of the photodiode


The cone above tested with different photodiodes :
Tested with BP104 the received voltage is improved 20 times
Tested with PD410PI the received voltage is improved 16 times
Tested with BPW41N the received voltage is improved only 15 times.
Perhaps because of the thick encapsulation that makes it impossible to come close enough to the light sensitive chip.
Tested with SFH 2030F the received voltage is improved 6.4 times.

An advantage of cones is perhaps that they will still work when wet or steamed ?

Testing cones with different types of reflecting surface :
Copper 20 times
Inside surface of potato chips bag (aluminum coated plastic) 20 times
Outside surface of potato chips bag (red painted) 10 times
Plastic transparent OH-sheet (white paper under) 14 times non metallic
White paper 3 times

The more sensitive you make the receiver the more sensitive it will become to lamps and jammers and atmospheric disturbance. And at last you will blow yourself up.
Therefore, try improve the transmitter's output power first of all.

You must shield away any direct sunlight from shining directly on the photodiode or else there is a risk of blowing your head off.

 

 

5 Connect more photodiodes in parallel in the receiver.

4 photodiodes gives double the distance.
The advantage over using lenses or cones is that you get a wider view angle.
And no trouble aiming the receiver. But it cost more.

The more sensitive you make the receiver the more sensitive it will become to lamps and jammers and atmospheric disturbance. And at last you will blow yourself up.
Therefore, try improve the transmitter's output power first of all.

You must compensate for the increase in DC current caused by light from the sky and surrounding, by shielding that light away.

 

6 Connect more receivers and transmitters in a chain.

You can reach targets 3 times more distant if you use 3 receivers and 3 transmitters in a chain. The disadvantage is that the delay time is 3 times longer.

Transmitter-----Receiver/Transmitter-----Receiver

You can also use chains to hide your own position. The enemy can then only see the visible red light ? from the last transmitter in the chain. But they can't see the position of the first transmitter in the chain, and will shoot at the wrong target.

 

7  Use multiple LEDs in parallel and no lens in the transmitter.

The shooting distance will be increased with :

Where N is the number of LEDs.


The advantage is a wider beam of light.
And the disadvantage is a more complicated circuit.
Just rise your hand and push the button without any complicated aiming.
Smaller in size. A pocket weapon.

Sometimes a wider beam is a disadvantage if you have planted more than one receiver and only want to activate one.
But you can solve that trouble by using cheap microprocessors that measures a unique pulse distance coded value.And every receiver has its own value.

      

The bipolar transistors above works as current generators, and the current is
(UZener - 0.7) / RE

The forward voltage for a LED (at high peak currents) is higher than at normal use, which means that you must use higher voltage, see the datasheets.
The forward voltage for 10 serial connected LEDs is perhaps 25 - 45 Volts.

A bipolar power transistor can have 1000 times higher leakage current than a power FET, (see datasheets). If you skip the power FET in a simplified construction, then make sure that the LEDs are not emitting light from leakage current, that can help the enemy find your position.
Always connect a resistor in parallel with the LEDs.

 

Improvement with a cone.

A reflecting cone around the multiple LEDs will help concentrate the light beams in the same direction. See the picture below.

My own testing shows that the amplification is 6 times for a narrow cone of about  +/- 2 to 5 degrees view angle.
A wider cone angle of +/-10 degrees will only give about 2.5  times amplification.
(Measured with an IR383 LED that has +/- 10 degrees view angle)

The bad news is that the cone must be longer the narrower the cone angle.
And the length is proportional to the diameter of the input end, which means that you must use a longer cone if you use more LEDs in parallel.

An amplification of 6 times means that 17 LEDs used together with a cone will do the same job as 102 LEDs without any cone.

The disadvantage with a narrow cone angle is that it also will shrink the view angle for the LEDs. And you must use a sight for aiming.

 

A disadvantage with multiple LEDs in series is that you need higher voltage or many batteries or a voltage converter circuit. A voltage converter circuit has the disadvantage of a charge up time of tens of seconds. The time you must wait before you can shoot.

 

 

 

Two types of transmitters

Type 1 :   One LED and a lens
Type 2 :   Multiple LEDs but no lens

A lens can increase the distance 5 to 25 times dependent on type of lens.
Which is equivalent to 25 to 625 LEDs if you use the other type of transmitter.
Because the distance = D0 * SquareRoot( Number of LEDs )

 

 

Lenses

Lenses can be used to increase the shooting distance for your remote control.
You can take lenses from cameras or magnifying glasses.

Two parameters describes any convex lens.
The burn width. f
The diameter. d

The burn width f is the same as the distance from the center of the lens to the target when you try to ignite fire from the sunlight.
The burn width can easily be measured with the sun, or anything very far away focused and projected on a screen.


This is the mathematics you need to know to do your own calculations.

The target in this particular case is the receiver.

Adjusting the focusing of the transmitter lens :

It can be hard to adjust the focusing of the weak LED's lightspot on a screen or target 300 meters away. But if you understand the formula above it becomes easier.

As you can see from the formula, the 1/a is almost equal to zero for targets very far away, which means that 1/b is almost equal to 1/f.
Which means that you first should measure f  with the help of the sun or anything else very far away.
And then adjust the distance between the center of the lens and the LED, to approximately f  minus the LED radius. ( f - 2.5 mm )



What's the diameter of the projected light spot ?


Lenses for receivers

It's the aiming accuracy that limits the usable burn width of the lens.
And a thumb rule is to keep the f  very short  (< 10mm) in order to get a wider view angle.
It's possible to put multiple lenses together to get a shorter burn width f.
And the view angle also depends on the size of the photodiode chip.


Cut a 10 mm diameter LED with a saw and clean and polish and you have a very cheap lens that you can use.

 

 

 

Conical amplifiers and optical fibers

 

 


A 90 degree cone can't amplify because it will reflect all the incoming light.
There is an upper limit of cone angles that we can use.

 

The light is concentrated to the output end of the cone, but with increasing angles.
A typical flat surface type of photodiode have a view angle of about +/- 60 degrees. And that's what sets a limit to how many bounces, and how wide cone angles we can use.
For one bounce the cone angle must not exceed +/- 30 degrees.
For two bounces the cone angle must not exceed +/- 15 degrees.

If you use the cone together with an optical fiber.
The fiber have a view angle of about +/- 25 degrees. And you must use a narrower cone for optical fibers.
For one bounce the cone angle must not exceed +/- 13 degrees.
For two bounces the cone angle must not exceed +/- 6.5 degrees.

Sooner or later the number of bounces will reach a limit where the angle becomes greater than 90 degrees and the light is reflected back to the transmitter. There is a limit to the effective length of the cone.

 

Testing a cone and a BP104 photodiode :
No fibers.
The amplification of the cone is measured to 15 to 20 times, for cone angles between 10 to 60 degrees.
With perhaps some voltage tops at different angles if there is any explanation.

 


 

Cones and 2mm fiber tested together


The reference amplification is 1.0 measured with only the photodiode, and no cones or fibers.
And the cone length is constant 40mm.

The yellow field is below the +/- 13 degree limit described above.
And the top voltage at 12.6 degrees is below the next +/- 6.5 degree limit.
The pink field perhaps only works when the cone is not perfectly aligned towards the transmitter.
Or perhaps because of a rough reflecting surface inside the cone.
Which perhaps means trouble in aiming the receiver if you ever intend to try these angles.

And in theory the best cone angle is perhaps somewhere below the critical angle if you count on aiming inaccuracy. But I leave this for future experiments to find the truth.

It seems like the cone angle is more critical or important  when used together with a fiber.

 

Conclusions :

  • A flat surface type of photodiode with no built in lens is the best choice.
  • The shooting distance can be improved 4.5 times with a cone.
  • You get about 0.5 to 0.7 times the shooting distance if you also use an optic fiber.
  • If you use an optic fiber, the optimum cone angle is between 10 to 22 degrees.
  • It's possible to build the receiver from non metallic matter, invisible to radar.
    And immune to impulse weapons. (Non metallic cones tested)

 

 


Optical fibers tested

The advantage of optical fibers is that you can make the receiver invisible to radar since there are no visible metallic parts. And also immune to impulse weapons that are used to neutralize electronics. (including unshielded electric blasting caps). And also immune to EMP from nukes.

 

The manufacturer of a 2mm diameter fiber says that the damping is 500dB/km
But it is probably not the same damping for IR as for visible light.

By measuring the signal strength for two different lengths of this fiber can I calculate that :
Received Voltage  = 0.4038 * e -0.00181*Length

But there is a mismatch between the 2mm fiber diameter and the size of the sensitive chip (2.2 x 2.2 mm) of the BP104 photodiode that damps the signal. And when testing with a 5.3 mm diameter plastic PMMA glass bar instead, the voltage is about 1.66 times higher than for the 2 mm diameter fiber.

Corrected approximative formula :

Received Voltage  = 0.67 * e -0.00181*Length

Length in millimeters

For zero length the damping is 0.67 which means that about 33 percent of the light is lost somewhere. By reflection when passing through the end surfaces of the fiber, and leaking light at the bends.

 

Conclusions :

For a typical 400 mm length PMMA glass bar about 70 percent of the voltage is lost because of the glass bar.
And the shooting distance is decreased to 50 - 55  percent.

With a 2mm fiber of the same length, the shooting distance is decreased to 35 - 40 percent because of mismatch between the fiber and the photodiode.

A 5mm diameter PMMA glass bar cost about $2 per meter.

 


A cone is only effective when the light beams are in parallel, and that's not the case for optic fibers or glass bars.
But the ending of the glass bar above will give about 30 percent higher received voltage.

 

Tips :
Clean the cut end surfaces with sandpaper and then scratch against a white printer paper for final polish.
Don't bend the glass bars with too small bending radius, because that will make the light leak or be reflected back. Use a hot air gun. Try avoid over heating because it creates gas bubbles inside the plastic.

 

 

 

 

Optical components :

For the receiver :

Use types with daylight filter if you use IR-light. That will lower unwanted signals to 50 %.
Never trust the speeds on the datasheets, you can use frequencies up to 50 - 100 kHz.

The photo receiving components becomes faster with higher voltage across.
That's something to remember if you have any trouble with slow components.
They also becomes faster if you use circuits with constant voltage across the photodiode (neutralizes internal capacitance), use current amplifiers instead of voltage amplifiers.

 


Photo diode

Photo transistor 3 pin

Photo transistor 2 pin
 

Photodiodes are the best, and phototransistors are piece of shit, but still useful if you haven't got anything else.

Photodiodes work well in any light condition, while phototransistors will give you trouble in extreme light conditions.

What happens in extreme sunlight ?

Photodiode

Works very well in extreme sunlight.

The electric current is typical 0.25 mA when the diode is directed at the sun.
Which means that you won't get any trouble at all when constructing the electronics.

The important thing is that the receiver is still working in extreme sunlight.

Photo transistor 3 pin

Becomes dead in extreme sunlight unless you compensate for the high DC with external circuits.

With no compensation the DC current is about 10 to 100 mA, which is at the end of limits of what the phototransistor is rated for.
There is a risk of barbecuing the transistor or consuming batteries too fast.

How to fix that trouble ?

The simplest and best solution against that is to only use the photodiode between the collector and base pins, and never connect the emitter pin.
Use the transistor as a photodiode.

Another alternative is  to use a more complicated amplifier stage that measures the DC-current and compensates by connecting a negative electric DC-current to the base-pin.

A third alternative is to shield away unnecessary light, see 2-pin phototransistor

Photo transistor 2 pin

Any receiver built around a 2 pin transistor becomes dead in extreme sunlight, unless you shield away the sunlight.

Piece of shit.
You can't connect this device like a photodiode since there is no base pin.
And you can't use a more complicated amplifier stage that balances out the DC-current since there is no base pin.

If you still want to use it, then you must always shield away all unnecessary light from unwanted directions.

The good about this type of phototransistor is that it is easy to find everywhere, in any occupied nation.

Double photo transistor 3 pin
Used in a PC-mouse

or

Put a painted black tube around the phototransistor.
If you limit the viewing angle to 10 degrees instead of 120 degrees then the daylight DC is 1% of it's original value.

But there is more work in aiming.

 

What happens in extreme darkness ?

Photodiode

Works very well in darkness.

Photo transistor 3 pin

Any amplifier stage built around a phototransistor becomes dead in darkness if there is no bias current to establish a DC working point for the amplifier stage.

Since the photodiode part of the transistor can't deliver the necessary bias current, you must do that with an external resistor 1-10 MOhm connected between the base pin and the collector pin.

 

Photo transistor 2 pin

Any amplifier stage built around a phototransistor becomes dead in darkness if there is no bias current to establish a DC working point for the amplifier stage.

Since there is no base pin, you must deliver the bias current through a LED illuminating the photo transistor.

An extra LED at the receiver end.

A PC mouse has two built in IR-LEDs that you can use.

The bad thing is that leaking IR-light can show the enemy where the receiver is.

Notes !

Even if a receiver works well in extreme sunlight, you should always try to shield away the sunlight for safety reasons.
That will lower the electric noise and atmospheric disturbance with a factor of 15 times more safe.

Piece of shit, or not ?
Phototransistors are still useful as long as you aim them in the right direction, far away from any direct sunlight. And always put them inside a painted black tube to limit the viewing angle. That will lower the DC current 100 times.


Testing to build a receiver from a computer mouse.


IR-LED and 3-pin double phototransistor close to each saw wheel.

 

Let's build a roadside potato


A black painted copper plate is bent into shape and then
solder and glue an IR-LED and a phototransistor in place.

A black painted (inside) U-shaped aluminum plate and a sheet of glass and a wood stick is glued together.And then cover with polystyrene. Paint the potato and it looks like a stone. Ready to be planted at the roadside to kill the enemy.

 

Potato testing results:

The potato is half dead and useless until I connect electric current to the internal LED.
That injects the necessary bias current to the phototransistor so it can start working.
I cant see any leaking IR when testing with my digital camera. That's positive for the resistance.

In the computer mouse I took the phototransistors from, there is two slow phototransistors at each saw wheel, but also an extremely slow phototransistor at the finger wheel. And perhaps finger wheel transistors are too slow to be used at 100 uS pulse width ?
Compared to the photodiodes I have tested before, these mouse-transistors are very slow, but still useful for the resistance.
(The speed can be increased with higher voltage across the phototransistors.)

DC measurement

89 uA DC current through the phototransistor when the potato is directed at clouds in the sky.
180 uA DC at 30 degree angle away from the sun, means 1 volt across the serial resistor (5.6k) and 4 volts across the phototransistor.
That's the 30 degree angle limit you need to remember for this particular potato.
But you can lower the angle with a longer tube in front of the phototransistor.

Any closer to the sun and the current rises quickly.

5Volts across the serial resistor when directed at the sun, (saturated and paralyzed transistor.)

 

AC measurement
Measured and calculated performance tells that the potato will have about 20 or 40 times S/N ratio dependent on how you measure, at 172 meters distance with no filters if you use a transmitter that consists of a IR383 LED pulsed with 2A current and a 60 mm diameter lens.

But usually there is a filter included in the receiver which means higher S/N ratio.
And we can use a longer shooting distance.

This potato was never tested together with the receiver circuit on this page because it is not dimensioned for the higher sensitivity of a phototransistor.
But you can use the circuit if you lower the sensitivity.
To do that, change the component values in the RC filter stage after the input stage. Change the 47nF, 10nF or 2.7kOhm to other values.

 

Conclusion :
The mouse transistors are usable.
But you must choose the right place for the attack, where the angle against the sun is more than 30 degrees.
No trouble since the road is long, and you can choose the right or left side, and the suns path in the sky is predictable every day.

 

Suggested improvements :

Use asphalt or anything similar to make a watertight seal around the cable.
Nothing else will stick to the fat plastic cable.

 

 

Some tested IR photodiodes
With black filter against visible light.


Photodiode Daylight Directed at sun Relative shooting distance
LT536 54uA DC 269uA DC 1
BPW41N     1.05
PD410PI 36uA 250uA 0.85
BP104     0.89
SFH2030F 32uA 540uA 1.30
Measured from single devices.
Note the last one which is a black LED-shaped photodiode with a built in lens focusing in a narrower 40 instead of 120 degree beam. Which gives 30% longer shooting distance. But also higher DC when aimed at the sun.

Translation of the table above into absolute shooting distance:
With a single  SFH2030F photodiode and an IR383 LED from Everlight at 2A current, a lens diameter 65mm with focusing distance 160mm. 300 meters
And that's with the receiver circuit described on this webpage.

As described earlier it's possible to extend the shooting distance with a bigger transmitter lens, or multiple photodiodes in parallel or a lens or cone in the receiver in front of the photodiode.

You can buy photodiodes or take them from TV sets or other remote controlled equipment.

 

 

 

Some high power IR LEDs

Wavelength Name Output Angle Current pulse Manufacturer
940 IR383 900mW/Sr 1A 20 1A100uS Everlight
940 IR333/H2 700mW/Sr 1A 30 1A100uS Everlight
940 TSAL5100 1000mW/Sr 1A 20 1.5A100uS Vishay
940 TSAL6100 1000mW/Sr 1A 20 1.5A100uS Vishay
940 ELJ-940-211 1900mW/Sr 1A 15 3A10uS
1.5A continuos
Roithner Lasertechnik
950 ELD-950-525 160mW/Sr 100mA 20 2A10uS Roithner Lasertechnik
940 520E940C 30mW/Sr 10mA 22 ? Weblink
940 L-7104F3BT 70mW/Sr 50mA 34 1.2A 10uS Kingbright
950 ACULED VHL IR2 390mW 700mA
Continously
? ? PerkinElmer
940 OED-EL-1L1 120mW/Sr 100mA 20 1A Lumex
940 OPE5194WK 120mW/Sr 100mA 20 1A100uS  
890 TSHF5210 1400mW/Sr 1A 20 1.5A100uS Vishay
870 TSFF5210 1800mW/Sr 1A 20 1A100uS Vishay
855 ACULED VHL IR1 880mW 700mA
Continously
? ? PerkinElmer
850 TSHG5210 2300mW/Sr 1A 20 1A100uS Vishay
850 SFH4550-FW 9000mW/Sr 1A 6 1.5A10uS Osram
850 HIR1363C 5600mW/Sr 1A 8 1A100uS Everlight
850 HIR383C/L212 500mW/Sr 100mA 6 1A100uS Everlight

 

IR LEDs are available in wavelengths between 700 and 7000 nm.  But 880nm and 940nm are the most used because of the sensitivity peaks for these wavelengths in the photodiodes. See the picture below.
The shortest wavelength types (880 nm) are visible to your eyes in darkness like a glowing cigarette.
Use 940nm if you want light that is invisible to the enemy's eyes.
But IR light  is visible to the enemy's TV cameras, and also visible in ordinary digital cameras.

 


The receiver's photodiodes are most sensitive to 880 or 940 nm wavelengths.
If you use any other wavelength then the shooting distance can become shorter.
But you can compensate by using a LED with more output power.

 

Daylight filter :
Is a black plastic matter used in photodiodes, and phototransitors, and you can also find and take it from the front of TV sets, remote controls, DVD VHS equipment.  Useful if you want to hide the receivers or transmitters.
Daylight filters are no miraculous cure to anything, because both the sunshine, daylight and lamp light consist of big amounts of IR light. The right word should rather be visible light filter. Useful if you want to filter out light from visible LEDs and lasers. Or want to hide IR components behind a black surface.
My own testing shows that you can win 2 times more safety when using photodiodes with daylight filter. Perhaps because 50% of the emitted light (the visible) from a lamp is filtered out.

Links to LEDs and datasheets

http://www.vishay.com

http://www.everlight.com

http://www.roithner-laser.com  LEDs from 7.0 um IR to UV

http://www.roithner-laser.com/LED_diverse.htm

http://www.lumex.com

http://www.epitex.com/global/index.htm

http://www.optodiode.com

http://www.hebeiltd.com.cn/?p=ir.led

http://www.optoelectronics.perkinelmer.com

You can buy IR LEDs or take them from TV remote controls or other remote controlled equipment.
The LEDs from TV remote controls usually have a wide view angle.
And in fact it's possible to use the TV remote control to ignite the bomb, but you will not reach the same long shooting distance.

 

 

 

Improved safety


The amount of light that reaches the photodiode is proportional to the space angle that the photodiode can see. Or in other words to the light emitting environment area that the photodiode can see.

If you limit the view angle to 10 degrees instead of 120 degrees then the daylight DC is 1% of it's original value. ( 0.2 mA instead of 20 mA for a phototransistor )

And the received signal voltage from unwanted wide angle light from jammers or lamps or atmospheric disturbance is also decreased to 1/100 of it's original amplitude.

For more safety and in order to lower the DC-current, can you put a black painted tube around the photodiode or phototransistor. The tube will limit the view angle, and shield away lamps and sunlight that can cause unintentional ignition, or too much DC-current which limits the battery lifetime. Always shield with aluminum foil against electric noise.


Layers of plastic tubes, aluminum foil and heat shrinking plastic tubes.
Apply pressure at the cable shield to make good contact.

The longer tube the more safe, but it also means you must aim it more precisely the longer the tube.

Use non-glossy black paint from a marker pen to paint the inside of the tube, to damp reflected light.



 

 

Safety :
Unintended activation of the receiver can be caused from bad electric shielding, moisture, bugs, lamps, power cables, cordless phones, radio transmitters, vehicles with switched light system.

Whenever a car drives near a fence it creates impulses from its lights.
And anything that comes between the sun and the receiver (a bird or a fly or grass or bushes) can cause the same type of impulses.
But you can remove impulses that has too long rise time with an electronic filter.
The circuit on this page is intended to receive short 100uS pulses while most natural sources creates pulses wider than 10 mS.

"The receiver circuit on this page did not ignite from a double fluorescent tube lamp 2*36W at 1.2 meters when tested." That's high power 100 Hz at close range, and sharp impulses every 10mS.

A mosquito which moves its transparent wings at 700Hz creates 1.4mS wide pulses.
I think this circuit is safe, but you should not trust that and instead do some testing.

 

The most important source of disturbance are lamps, at 100 - 120 Hz.
Fluorescent tubes also emits short impulses every 8 - 10 mS

The ordinary 60 Watts lamps you use at home are filled with gas, which means that they contain a light emitting plasma. The glowing wire itself won't emit frequencies above kHz, but the plasma can emit oscillating light at high power and at high frequencies.

I have measured frequencies up to 160 000 Hz at high power from these lamps.
And the tricky thing is that only some of those lamps oscillate. Which is a trap that can fool you to believe that lamps are safe, until the day you find an oscillating lamp and blow yourself up.

A torch can have gas filled lamps. Never use a torch (electric lamp) when planting receivers.
I have tested a torch that emitted 700 HZ disturbance whenever I hit the casing with a finger.

Ordinary lamps also emits light at IR wavelengths.

 

How to become more safe ?

1 Shield away any unnecessary light from the receiver's photodiodes, for example by twisting a painted black paper around the photodiode. Never let any light from the sun or lamps hit the photodiode.
The risk decreases with the square of the distance from the lamps.

2 Use two receivers in parallel and of different type, with the relays connected in series.

3 Make the receiver less sensitive and increase the output power from the transmitter.
Use links of receivers/transmitters between the receiver and transmitter.

4 Tell innocent people to keep away.

5 First plant the  photodiode and then keep away from it and don't touch it anymore, then connect the battery and at last the blasting cap. Do in inverse order when disarming.
Bad connection in the battery wiring can cause glitches in the electronics and activate the receiver.
Filter capacitors may prevent that from happening.
Tinned wires gives better connection than pure copper when cable ends are twisted together.

6 Never walk in front of the photodiode and don't kick up sand and dust.

7 Electronic circuits can have energy stored in capacitors which means that they still can emit light or connect a relay even if the battery is disconnected.

8 Someone else can have planted a receiver, don't play with the trigger.

9 Turn off your cordless telephone before you start working, and never use any kind of lamps or electronic displays.

10 Protect against moisture, paint the circuit board at both sides.
Military people use fat or Vaseline filled, plastic covered metal tubes to protect cable ends that are twisted together.

11 Shield against electric disturbance, use a metal box, shield the entire photodiode with layers of aluminum foil and plastic tubes. The aluminum foil must be connected to the wires shield, and connected to ground on the circuit board. The box must be connected to the same ground.
That's very important !


Solder the wire for highest safety.

12 Never connect to the same battery as other types of equipment. For example a car battery.

13 Always test new equipment for a while to see if it is safe to use.

14 Multiple cascaded simple RC filter stages is often a better solution than more complicated filter designs because they will not ring like a bell when receiving impulses from the enemy's impulse weapons or other sources of disturbance. Use non ringing filter designs.

15 You can improve the safety by only using the receiver sensitivity that is really necessary.
I f you shoot at 150 meters then make the receiver sensitive enough for a maximum distance of just above 150 meters.
I f you shoot at 300 meters then make the receiver sensitive enough for a maximum distance of just above 300 meters.
This means that you get 4 times improved safety when you shoot at 150 meters.
A simple solution to adjusting the sensitivity is to use a single photodiode at 150 meters and 4 photodiodes at 300 meters.

 

 

Improvements

There is always an arms race.

 

Using a microprocessor to increase the safety level.

A single chip microprocessor cost $2 and you can program them at home if you buy a programmer for $30 - $300 that you connect to a PC.
All the knowledge is available online.

http://www.microchip.com    microprocessor

http://www.elnec.com  programmer

You must change the construction to use pulse distance codes and measure the time between each pulse.
You can give the receiver an unique code that will activate only this receiver but no other receivers. The PIC will make it impossible for the enemy to blow up your minefield with twinkling lamps.


The same circuit as before connected in logical AND with the red new circuit.

 

Power FET transistors
If you need protection against detonation waves that shakes the relays and ignites the bombs then try a power FET transistor instead of a relay. And perhaps change to negative voltage because the N-channel FET circuit becomes simpler with negative voltage.
Remember that if you drop a relay on the floor there is a risk of igniting the bomb and blowing yourself up.

 

Use color filters and colored LEDs.
The experts call them interference filters and they have a narrow bandwidth of 20 nm.
Theoretically this means that the enemy must use (940 - 400) / 20 = 27 times more power.
Or 27 different big lasers instead of one, if there is place on the vehicle.

Interference filters can also be used to damp broad band disturbance from lamps and atmospheric disturbance about 27 times. And improve the safety.

Perhaps it's possible to use a simple CD as a filter, because it acts like a interference mirror that deflects light with an angle proportional to its wavelength. This is for homebuilt filters in occupied nations.

 

Use a tone modulated system.
A tone modulated system is built like a spectrum analyzer of the superheterodyne type.
It is more complicated and expensive than a pulse system. And consumes more power and is also slower. But is also more safe. The enemy's jammer also needs thousand times more power to jam thousand times more channels simultaneously.


Tone system with programmable 5KHz --100KHz input frequency
High order  n = 5 -- 8 LP-filter 25--50Hz
High order  n = 3 -- 5 HP-filter to filter out 25--50 Hz at the input

The description of tone modulated systems will be updated in the future.
 

 

 

 

If you want faster ignition
Because that makes it easier to hit those fast moving vehicles.
Then you must use higher Voltage.

The delay time = K / Voltage2

It's square function.
10 times higher voltage doesn't mean 10 times faster, but instead 100 times faster.


Military blasting machine.
An electric capacitor is charged up to 600 Volts

The solution is obviously a charged up high voltage capacitor.

 

 

Comparing different solutions

Below are some calculated relative delay times.

Alkaline batteries :
67 batteries in series
67 * Ri = 10 Ohm
Voltage = 100.5 Volts
Cost = $45

Delay time = 58

The internal resistance is too high, which causes the long delay time.

Lead batteries :
8 batteries in series
8 * Ri = 0.4 Ohm
Voltage = 102.4 Volts
Cost = $100

Delay time = 4.7

Cost too much.

Electrolytic capacitor
Low impedance 470 uF
Ri = 0.040 Ohm
Voltage = 100 Volts
Cost = $2

Delay time = 4

50 times cheaper.
And a little bit faster ignition.

Electrolytic capacitor
Low impedance 100 uF
Ri = 0.040 Ohm
Voltage = 200 Volts
Cost = $2

Delay time = 1

4 times faster at the same cost.

 

Conclusions :
The fastest and cheapest solution is to use an electrolytic capacitor.
And use an electronic circuit to generate high voltage from a few alkaline batteries as shown below.

The circuit below is also used in photo flashes, which explains why some bomb makers take the circuit from a photo flash instead of building their own circuit.

 

Simple 5Volts to 90 Volts DC to DC converter .


The converter is a self oscillating single transistor stage, the second transistor is used only as a switch to turn off the converter at 90 Volts. Because you must turn off the circuit when the capacitor is fully charged or else something will be destroyed from overvoltage.
Use a diode and transistor rated for at least 100 Volts.

If you have no high voltage transistors then you can instead try the circuit below.

 


This circuit can be built from a ferrite rod antenna from an AM-radio.
And a 30 Volt small signal transistor.
And the efficiency is near 95% if you exclude the losses in the 2k7 bias resistor and the output resistors and the diode.

The electric high voltage energy is stored in the electrolytic capacitor at the output.

The 56 Ohm resistor is necessary against crazy oscillation.
Crazy oscillation can also occur if there are too many turns in the feedback coil.

 

The resistors at the output is used to select the voltage that turns of the circuit.
And the voltage at the transistors base is then 0.55 - 0.6 volts.
(Sensitive to moisture because of the 1MOhm resistor. Insulate well.)
You can also use a  zener diode instead of the resistor network. That will give a more temperature stable voltage output.

This circuit is almost foolproof. If it doesn't oscillate then you have probably connected the wires from the feedback coil wrong. But that's easy to fix.

 

The coil


The important thing is not the number of turns, but instead that you use the full length of the ferrite rod. And the efficiency is improved if you use a single layer for each coil.
If your ferrite rod has a different length or if the wire diameter is different then you should change the number of turns.
A layer of paraffinated paper between each coil makes it easier to wind up the wire.

You must shield the circuit against leaking power that can activate the receiver circuit.
Use a chain of electrolytic capacitors and resistors to filter out the high current impulses from the battery voltage.

And you must also shield against leaking radio power that the enemy can use to find the circuit.
A toroide (ring shaped) instead of the ferrite rod emits less radio power.
But in an occupied nation the only thing you can find is perhaps the ferrite rod that you can take from any radio receiver.

 

 

What size of capacitor to use ?
Try ignite your blasting caps with a charged up capacitor and find out the minimum capacitance that ignites your blasting caps. And then use a capacitor that is 3 - 10 times bigger.

Don't use too big capacitor because it means shorter battery life, because of leakage current in the electrolytic capacitor.

The stored energy = 0.5 * Capacitance * Voltage 2

Which tells us that you get only 25% energy if you charge up your capacitors to 50 V instead of 100 V.  Use as high voltage as possible.

A capacitor of 1000 uF (=0.001000 F) has a stored energy of 5 Joule at 100 Volts
Which is the same energy as 0.5 kg hammer has when it is dropped from a height of 1 meter.

 

 


Toys for men

Foldable homebuilt IR-remote control

The modular and foldable design makes it easy to change to a lens of bigger or smaller size if necessary. And helps to hide the transmitter in the pockets.


 

This transmitter was built only for evaluation.

If you are planning to attack vehicles on a road, then perhaps a simpler construction is better.
A simple pre-aimed tube with a lens and the electronics inside. And an electric cable to an external pushbutton. This means that you don't have to focus too much on aiming, but instead can concentrate on timing. A pre-aimed transmitter is preferable if used in darkness. And perhaps a non-metallic construction is the best.

 

 

A simple and cheap watertight electrically shielded recloseable box with good electric connection.
Use it in combination with cable glands.

 

 

 

IED jammers have made all radio types of remote controls useless

The radio jammers are standard military equipment. Search for "ied jammer", "warlock"
http://thehill.com/pentagon-to-spend-350-million-on-next-generation-jammer

 

Advantages of optical remote controls :
Immune to jammers, because unlike radio waves it's easy to shield away the light from any unwanted direction.
Long shooting distance of up to 10 kilometers.
Cheaper than any radio system.
Can also be made invisible to radar and immune to electromagnetic impulse weapons and EMP from nuclear weapons.

 

Why is an optical system better than a radio system :
The attenuation of radio power (for frequencies above 2MHz) is proportional to the inverse of the fourth power of the distance between the transmitter and the receiver, 1/R4. (because this is not free space propagation, 1/R2). (Search for : Ground plane reflection, Radio propagation.)

Since the resistance's transmitter is located at least 20 times further away from the receiver than the enemy's jammer, it can be estimated that the resistance's transmitter must emit 160 000 times more radio power to generate the same signal strength in the receiver.
If the resistance instead use an optical system then the opposite is true. The enemy need 100 to 100 000 000 times more power than the resistance. Because the war has changed from being a question about the distance to the receiver to a question about free sight.
This means that the enemy has lost it's main advantage in the jammer war against the resistance's remote controls.
The optical system is also extremely easy to build and very cheap compared to a radio system. It's possible to take electronic parts from a computer mouse and a TVs remote control to build the device. Electronic parts which are easy to find in any occupied nation.

The immunity against jammers can be improved further with tone selective systems, or narrow band color filters, or microprocessors and pulse distance coding.

 

Calculation about immunity against jammers :
The signal from the jammer will be damped :

4 times from the fact that the jammer's light must be aimed at and travel first to the transmitter's location and then be reflected back again. Which is double the distance compared to the light from the transmitter. (Square law of attenuation.)

* 100 times from the fact that the environment is no perfect mirror, which means that the jammer's signal will be reflected in random directions instead of being reflected back to the receiver.

* 1 - 4 times because some light will be absorbed or lost out in space instead of being reflected.

* 100 - 1000 times because the enemy does not know where the transmitter is located and the jammer must emit its light in a wider beam compared to the transmitter.
(left side 90 + right side 90)  * height 20 degrees instead of the transmitter's 2x2 degrees

Mean value of about 4 * 100 * 2 * 500 =  400 000 times more power must be emitted from the jammer compared to the transmitter. And since the transmitter's LED consumes 3 Volts * 2 Ampere with a dutycycle of 1.8 percent = 108 mWatts  can we estimate that the jammer must consume about 43 kWatts. That's not portable or possible to install on every military vehicle, which means that the only solution is special jammer vehicles.

But :
That's for the enemy's jammer light being reflected back from 300 meters.
At 10 meters, the enemy need only 50 Watts to blow up your bomb.
Your countermeasure against that, see below or this link.

 

The receiver becomes more immune to jammers if you aim it  in a direction where no close objects are in the view angle. See the picture below.
The best is to put the transmitter up in a tree or on a mountain or hill or rooftop.

 

 

Why use remote controls ?

An electric  cable is detectable with airborne radar that can penetrate the ground to a depth that is equal to the wavelength used by the radar. If the enemy can see a cable then they also know that there is a bomb. You should not give the enemy those lines on the radar screen that point out the cables and bombs.
A 300 meters long low resistance cable for the blasting cap is also more expensive than a remote control.
It takes more time to dig down a cable than it takes to plant a remote controlled receiver.
A cable is the track that the enemy afterwards can follow to your home or hidden position. Which makes it impossible to fire the bombs from your home in urban areas and then try to melt in and hide.
A cable can't be used in urban areas or in vehicle bombs or coke can garbage bombs standing on the asphalt because you don't have the time to hide and dig down the cable in secret.
You get more opportunities to fire the bombs in secret if you use remote controls instead of cables.
And the enemy get more hell.

It's about becoming more effective.
Save time.
Save money.
Improve the killing efficiency.

 

 



 

What to connect to your IR remote control

No more foot patrols for the enemy


Connect to the IR remote control receiver and plant where you want to give the enemy a surprise.
The advantage is that no innocent people will be hit.
And since you instead of a dumb tripwire decide when to fire the mine it can be fired whenever the enemy come close enough. Sometimes a tripwire is useless because the enemy is coming from the wrong direction or see the tripwire. Or is expecting a bomb and acts with caution.
It depends on the environment if you should use a jumping grenade or if a non jumping grenade is usable and  effective enough. The grenade is ineffective if it detonates underground.

Screws and nuts are probably the cheapest projectiles to fill up the grenade with.
And you can buy them almost everywhere in big quantities.

 

If you have no high explosives
Then try instead a simple homebuilt cannon built from a steel pipe, and use gun powder, matchheads or mixtures of aluminum, magnesium powder and oxidizer to launch the screws and nuts.

 

 

EFP

If you read the US military's own statistics then you will find that EFP is 6 times more effective than the big bombs at killing US troops and vehicles.
And if you try use some mathematics then you will probably find that you can save both time and money by using EFP instead of big bombs.
It is better to put your men in work to manufacture more effective weapons instead of wasting their time and lives on the battlefield with ineffective weapons.

EFP is also useful against fortified buildings.
If you can't come near with a big bomb because of concrete blocks around the building, then you can instead launch an attack from a distance with a car filled up with EFPs, because EFP is a cannon.

 

The shape of the dish decides what happens.

The jet is a special case in which there is no lasting projectile.
And it will disintegrate and lose its penetration capability after a relatively short flight.
The countermeasures against jets are easy, but the same countermeasures don't work against EFPs because EFPs are projectiles. EFPs can penetrate armor very far away, like a cannon.

 

First some proof of the fact that EFP is easy to build at home and that EFPs don't have to be circular or machined with precision in iran.
An explosives filled aluminum profile tube EFP used to cut concertina wire and destroy mines.
Developed in the United Kingdom by Alford Technologies and is intended for use with both standard army and Special Forces units,

 

Patent : 6606951   EFP antiarmour mine

 

 

 

A possible easier way to build EFPs

The resistance consist of amateurs which most of them are unskilled in using tools or shaping EFP liners. Which means that if a a weapon need to much work then noone will build it.
And they will rather waste 1000 kg of explosives on a big bomb for the ears and eyes that won't kill anything.
What you need is a simplified EFP construction and it's the liner that must be simplified.

You can't find circular dish shaped liners ready to use anywhere, you can't buy them.
But you can find steel bars everywhere.

The clothes-pin shaped EFP from patent 4649828 tells us that there might be an easier way to build EFPs.


Clothes-pin EFP from patent 4649828

 

Simplified Improvised Multiple EFP  SIM-EFP

At shorter roadside bomb distance there is no need for any aerostable cone tailed projectiles, which means that the liner can be simplified.

A SIM-EFP is built of simple cut and bent steel bars.

A SIM-EFP is a construction that fits in between the linear cutting charge and the platter charge.
And the main difference is how much the rectangular liner plate is bent. See picture below.

A simplified EFP has a thicker liner and thicker explosives layer.
If there is any trouble with breaking up in fragments then try a thicker liner plate or a rounded back.

Thumbrule :
The penetration in armor steel is the same as the projectile length.
Which is half the length of the steel bar.

 

Impact angle and penetration in armor
One of the main reasons for using circular liners is that at cone tailed projectile is aerostable and always will hit with its nose first for maximum penetration. It can be used at a distance of hundreds of meters away.
Other EFP designs are not aerostable and can only guarantee maximum penetration at short to medium distance whatever that means. Below 100 or 20 meters I think.  But that is also the typical distance for a roadside bomb. Do an accurate symmetric job when assembling the simplified steel bar EFP and it will not tumble randomly as much.


The penetration is proportional to the length of the projectile.
Look at the picture and try to understand what is meant with the length of the projectile.

 

 

No trouble with timing differences anymore
If using multiple ordinary EFPs in parallel, then it's necessary to use a single blasting cap and equal length explosives filled tubing to cancel the timing differences that can destroy or aim some EFPs in the wrong direction. But SIM-EFP doesn't need any explosives filled tubing, because the entire construction is collected together in the same unit. This is timesaving when planting the EFPs.

                 

 

 

 

The SIM-EFP is by it's construction optimized for killing armored vehicles.
Because it launches a swarm of projectiles that are perfectly spread out for killing vehicles, and also projectiles that are optimized for armor penetration. See picture below.


A perfect spread out swarm of armor penetrating projectiles.
Everyone inside are hit, and noone will survive.
Longer timing error allowed.
Easier to kill fast moving vehicles.

Conclusions :
The SIM-EFP is a weapon that is easier to build, which means improved production. Easier to plant and more effective and timesaving at killing armored vehicles.

When the production of EFPs becomes too easy, then it will become the standard weapon instead of a rarely used special weapon. And that will improve the resistance's striking power and killing efficiency and force the enemy to abandon the roads.

EFPs are 6 times more effective than the big bombs at killing the enemy.

 

Trouble ?
You have to do some experiments about the optimal shape of the liner and explosives layer.
Make sure that the liner doesn't fold forward or get any other bad projectile shapes.
Try different constructions against a concrete wall and use the construction with the best penetration capability.

 

 

 

Try evaluate the design below, because it is so powerful that it will change the battlefield if it works.

Heavy tank killer ?


A simple bent steel bar with explosives attached.
Maybe a rounded backside profile to prevent the breaking up in fragments ?
Or a round profile ?

 

With this it's too easy to build a weapon launching a projectile half a meter in length. The penetration in armor is almost the same as the projectile length, which means that it can penetrate a heavy battle tank like Abrams or Merkava from a side attack.

It's flat design also makes it easier to hide in the terrain.

See the picture below that shows a circular and a flat EFP side by side.
Which one do you think is the easiest to hide in the terrain ?
If you have to dig it down ?

 

It's easier to create a long rod projectile from a flat EFP design compared to a circular EFP design.
Because it's easier to cut and bend a steel bar than it is to build a one meter diameter dish liner.
And perhaps the steel bar doesn't have to be bent at all (compare to a platter charge) which makes it a lot easier.

With this design you are not limited to attacking the heaviest tanks from the top or bottom anymore. You can kill them from a side attack.

An Abrams tank have a side armor at the lower part of 2 - 3 layers of 2.5 inch armor plates, which means about 7.5 inch (20 cm) armor steel, if you do not hit the tracks and wheels. The EFP projectile should be 20 - 25 cm in length to penetrate which means a steel bar of 40 - 60 cm in length.

Circular EFPs of that size are difficult to build. Which means that if you want a homebuilt heavy tank penetrator then you must abandon circular EFPs and try a flat EFP design.
Ask any expert in the workshop and they will agree.

If you got nothing else then take a railroad track. Send it like a projectile through the enemy's tanks.

Flat EFPs are only useful at short and medium roadside bomb distance because they are not aerostable.

Improvements :
Try weld the steel bar together with an aerodynamic shaped tail. Do your own experiments.

 

The flat EFP design is also an argument for redesigning nuclear powerplants because it's easy to build at home a weapon launching a projectile straight through a nuclear powerplant.
If you haven't learnt anything from Tjernobyl or the WTC already then there is no hope for you.
The reactor itself should be placed underground 10 to 20 meters below the surface in a safe nuclear powerplant design. That will also protect against airplane attacks. Another lesson from Tjernobyl is that they had to dig the reactor down after the disaster, so why not save some time and have it dug down before any disaster.

 

 

Explosives for the EFPs

You can take the explosives from military grenades and bombs.
The two most common explosives used are TNT and RDX.
TNT melts like candle wax at 70 degrees and can be casted into shape.
RDX is not castable and is therefor mixed with wax or TNT to make it castable.
And the RDX mixtures get many different names dependent on what it is mixed with and in which nation, (hexogen, hexotol, comp-A, comp-B).
Do not overheat if you don't want to blow yourself up, and remember that explosives are poisonous.
Try heat up the grenade in a watertank and the temperature will never go above 100 degrees.
Some grenades are filled with uncastable explosives and you should not try to melt it. And you must remove all heat sensitive primary explosives before trying to heat up the grenades.
If you don't know what type of explosives it is in a grenade then do a test on a tiny piece instead of heating up the entire grenade.

 

 

ANFO Ammonium Nitrate Fuel Oil or fertilizer bombs.
Ammonium Nitrate is used by mining companies for its good economy, and by farmers as a fertilizer.
It's cheap and effective for big bombs.
And perfect for a dug down bomb under the road.

The enemy can use metal detectors and high frequency impulse mine seekers to find bombs under the road, and you must use construction matter that is hard to detect, like wood or stone. Some plastic matter is visible while others are invisible.

Since the remote control is visible on the metal detector you must use a explosives filled plastic tube of about 10 meters length between the receiver and the bomb.
Or use a non-metal igniter that is not remote controlled. With the disadvantage of blowing up innocent people.

 

Two approaches :
1  Blow up the vehicle with a very big bomb.
2  Create a traffic accident by blowing up holes in the road in front of the vehicle when it comes at high speed.

As you can read on wikipedia and in the newspapers, most armored military vehicles are instable and causes traffic accidents. And the military must send their drivers to a driving school for heavy instable armored  vehicles.
The new mine resistant MRAP vehicles as an example have had the chassis lifted up and a V-shaped underside to deflect the detonation wave. And the armor is much thicker and heavier.
More weight higher up is a bad equation that makes the vehicles sensitive to bad roads. And they can't drive like car thieves anymore. And we can read about talibans escaping through the desert in ordinary cars because the MRAPs can't keep up the speed in the bumpy desert. And we can also read about a lot of lethal traffic accidents.

All you have to do to cause traffic accidents is to blow up holes in front of the vehicle, or make the vehicle jump and bounce down from a mountain or hillside.

New military vehicles are instable

 

Traffic accidents

Put  the men inside an elevator or armored car and also throw in some bench-vises or machineguns.
Shake and bake.

It doesn't matter how much armor the elevator or vehicle has.
The men inside will hurt themselves badly.

And it isn't necessary to penetrate the armor, just shake and bake.
Create traffic accidents.

 

 

Remote controlled RPGs

RPGs are an alternative to EFPs
If you fire a RPG with remote control then there is no need to care about the recoil or flames from the rocket.
And since it is pre-aimed it is just to push the button. And none of your fighters will risk their lives.

 

Point weapons like big bombs are easily disarmed while line Weapons like RPG and EFP are immune to the enemy's countermeasures.

In an effort to clear paths heavily mined by the Taliban, soldiers employed a weapon called a MICLIC, an acronym for Mine Clearing Line Charge. In one thunderous, ground-shaking boom, the weapon clears a path 300 feet long and wide enough for a tank. Breland said his company commander, Cpt. Mike Gold, had used 16 MICLICs in one day.

The remote controlled RPG and EFP can't be disarmed as easy as the big bombs, because they are standoff weapons that can be launched alongside the road to kill disarming vehicles and robots from far away.
And the work becomes at least 20 times harder for the enemy if they must clear a width of 200 meters instead of 10 meters alongside the road.
The big bombs are point weapons and you are safe if you are far away, but you are not safe from RPG and EFP.

 

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