Have you ever wanted to fire a projectile using the power of electromagnetism? Then this instructable is for you. In one of my old instructables, I show you how to build a coilgun, or gauss gun, from disposable camera capacitors and circuit board. Nowadays, disposable cameras are hard to come by, I had to buy the disposable camera shown in my previous instructable on ebay. Also, the coilgun in that instructable was not very powerful. In this instructable, I will show how to build a better, more powerful coilgun from scratch. The video below will complement this instructable with an explanation of how this coilgun works and a demonstration of it firing.
Step 1: How It Works
The coilgun works by introducing an extremely strong momentary electromagnetic field to a ferrous material. When the magnetic field is applied, the projectile moves to the center of this field. After it has moved, the field collapses and the momentum of the projectile keeps it moving out of the coil into the intended target.
Step 2: Tools and Materials
For this project, many different tools and materials are needed.
- Soldering iron and solder
- Wire strippers
Materials(Refer to the schematic)
- Assorted resistors
- 555 timer
- NPN Transistor (Almost any one will do)
- PNP Transistor(Almost any one will do)
- Assorted ceramic capacitors
- As many 200 volt rated electrolytic capacitors as you can find(The more the more powerful)
- Pen tube
- Copper enameled wire
- 11 volt Lipo battery
- 1.5 volt cell battery
- Silicon controlled rectifier
- Analog Meter
- Power transformer
Step 3: Assembling the Charge Circuit
The charge circuit boosts the low voltages from the battery into high voltages (200volts) that can be used to charge the capacitors. This charge circuit uses a 555 timer IC to drive two transistors that drive a power transformer. The driver circuit is attached to the 9 volt winding of the transformer and the 277 volt winding is connected to the bridge rectifier to charge the capacitors. To assemble the circuit, solder the components onto a piece of perfboard. Follow the schematic above.
Step 4: Assembling the Capacitor Bank
To assemble the capacitor bank, take all the capacitors and wire them in parallel. Connect all the positive pins together and all the negative pins together. Then, connect the capacitor bank to the bridge rectifier, MIND THE POLARITIES! The capacitor bank should be ready to use.
Step 5: Assembling the SCR Trigger Circuit
The silicon controlled rectifier (SCR) allows all the energy from the capacitors to be discharged into the coil very efficiently. Using a switch creates a spark, which wastes energy. Assemble the circuit according to the schematic. Use copper wire to build a holder for the battery. Add a big red button as the trigger in between the battery and the gate of he SCR.
To see when the capacitor bank is full, I used an analog gauge. I used a .25 megaohm resistor in series with the meter to make the needle hit red when the caps are fully charged.
Step 6: Building the Coil
To build the coil, wind approximately 200 turns of copper wire around a pen tube. Then, wire the the coil to the SCR circuit.
Step 7: Attaching Everything to a Frame
For this project, I attached all the components and boards to a piece of 2x4 wood. I drilled holes in the side of the wood to hold all the capacitors and I hot glued all the components onto the wood. Each individual board is connected by wire according to the schematic. If you are building this, you can build the frame or enclosure however you want.
Step 8: Firing!
To shoot the coilgun; first, you need to flip the charge switch to star the gun charging. This usually takes about 2 minutes. While the capacitors are charging, load the projectile into the pen tube right outside of the coil. Any ferrous material will work as a projectile(nail, screwdriver head, ect.). After the coilgun has charged, the needle will be on red. Then, you can pick up the gun, and shoot it at your intended target.
Disclaimer: This coilgun is dangerous and uses high voltages. I am not responsible for any harm inflicted on you or anybody else by this project. Build this only if you have an appropriate knowledge of electronics and common sense.
Thank you for reading, good luck!