CoilOsapien is an electric shock hazard!!!

This tutorial is intended for those Over 18 due to the dangerous nature of such a modification to your Robosapien. For this reason the instructions may not be a step by step guide but will allow those who have some existing technical knowledge the ability to use the same components I have used to complete the coilgun hack.


I take no responsibility for the way these instructions are used by anyone who attempts this modification. You will be required to work with potentially lethal voltage, eye harming laser diodes and fast moving projectiles, If you have any concerns with what is involved in working on this hack PLEASE DO NOT READ ANY FURTHER.

I originally had an idea to add a mini butane powered gun onto the right hand of my v2 but getting the gas/air mixture right for each shot was very difficult. I then began looking down the path of a small coilgun instead.

The following list is what I used for the hack, there are many substitutes you could make here.

  • At least one disposable camera with flash
  • 4 x photo flash capacitors (I salvaged mine from 3 other disposable cameras)
  • 0.4mm enameled copper wire
  • 2 x Ball-point pens (just the casings)
  • Electrical tape
  • A small servo
  • 2 x 5v regulators
  • SPST relay (Higher current handling if possible)
  • SPDT relay
  • LED
  • AA battery holder
  • 2 x softdrink lids (plastic)
  • laser module (any type will do)
  • small magnet
  • 2 x empty film canisters
  • Hot glue (this was my best friend!)
  • Hookup wire (some heavy duty, some light duty)

Most of this I already had at hand.

CoilOsapien Mod10
Flash Circuit1

Lets start by getting the charging circuit out of the disposable camera. Take off whatever cardboard wrapping is over it and crack open the case. Sometimes I have found these are only taped together and others you will need to use a screwdriver to get it open.

At this point you will confronted with a circuit the same or similar to the one on the left. Take care not to touch the leads of the capacitor or you may get a nasty shock. I would advise draining the by either shorting out the two lead with a screwdriver ( the lazy way), or using a 1w 1m resistor held across the leads with pliers (Note: Make sure tools have plastic handles.) The capacitor holds a charge of around 330v so it will give you a nasty bite as I found out on several occasions.

Take note of the battery polarity of the circuit, where the two switches are on the circuit and finally the polarity of the capacitor.

Now de-solder the capacitor and remove the flash tube and housing from the circuit. (Picture to the right)

Flash Circuit202
Flash Circuit3

Flip the circuit over and solder together the contacts of both of the switches so that they are constantly in the “on” position. (picture to the left) Now when you apply 1.5v at the battery clips you should get a voltage of around 220v where you removed the capacitor. You can use more than one battery for faster charging times but it will put out a much higher voltage and may damage the capacitors.

CoilOsapien Charge circuit

The picture on the right shows where I installed the battery clip, charge circuit and the capacitors. The battery fits perfectly between V2’s shoulder blades and I drilled small holes through his casing to put the capacitor leads through and mount them on his shoulders, I then ran wires to the charge circuit. I used hot blue to hold down the capacitors and attach the battery clip and charge circuit onto V2’s back.

Coil 1
Coil 2
Coil 3
Coil 4

Strip the pen to leave just the hollow casing. (inside diameter of pen 6.5mm)

Put one layer of electrical tape (1.9cm width) over the pen around 2cm from the end.

Using .04mm enameled copper wire wind a coil over the surface of the tape from one end to the other.

Cover the first layer with tape and repeat until you have wound ten layers of coil.

Time for the coil...


Once the coil is complete you can use hot glue to seal the front and back of the coil to make sure the windings don’t come loose down the track. I wound a few different coils before I settled on this one. I basically used trial and error and some educated guessing so it wouldn’t hurt playing around with some different coils yourself as different coil lengths, wire thickness and winding techniques will have a dramatic effect on the coilgun’s performance.

nextpage copy02

A coilgun uses a coil of wire and a pulse of energy to create a short, intense electromagnetic field to fire a ferrite projectile. The projectile is rapidly pulled toward the center of the coil when power is passed through it. When the power is cut (or expended) before it reaches the center the projectile will continue to move forward at speed and fire out the barrel.

There are many types of coilguns including those that use multiple coils in series and timing circuits to achieve maximum efficiency. CoilOsapien uses the simplest of the coilgun designs which is a single stage coil with no timing circuit.

What is a COILGUN?

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