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This is a project that I decided to try after getting the idea from David. This uses an electromagnet to pull a metal projectile towards it very fast, and then to release it to let if fly off.

If you want to learn more about coilguns or learn to make one yourself, check out these pages:

www.sixmhz.com How-to on making a coilgun and descriptions of his three-stage ones

Wonko Labs This is about making a coilgun for free. Mine is based off of this

• Setup
  • Unlabeled
  • Labeled
• Barrel
• Front of Barrel
• Meter
• Capacitors

A coilgun will shoot a projectile by creating a strong magnetic field, which an object is attracted to. The electromagnet is pulsed quickly. Coilguns are not widely used as weapons, because of a few disadvantages. These include long charge time and large size. And they could never stand up to the portability and power of gunpowder. However, they are useful because they create no sound whatsoever, except for maybe the projectile whooshing through the air or hitting it's target. Coilguns have been suggested for launching payloads into space. My coilgun is a single-staged one, which means that it consists of only one electromagnet and only one stage of acceleration. Many larger coilguns use multiple stages to accelerate the projetile faster each time. Each stage is pulsed right before the projectile enters it to give it a nice strong pull. These pulses can be triggered using light sensors and SCRs for high-volatage switching. Mechanical relays will not be fast enough to switch it. So, that's a little background on coilguns. Now check out mine!

Unlabeled

This is a circuit in this camera which will charge the energy capacitor. It amplifies the 1.5v from the batteries up to the 300v needed to charge the capacitor. Inside the camera, it is used to charge the flash. This produces the power to charge the coilgun.

A capacitor is like a rechargable battery. You can charge it up, and then discharge it, slowly or rapidly. This capacitor holds all of the energy to be released through the coil. This capacitor can hold up to 200 volts at 580 microfarads. Standard flash capacitors are 300-350 volts at 100 microfarads, and everyday capacitors can range from .01 microfarads to 100 microfarads, usually no more than 10-12 volts. Here is a picture of my big capacitor as compared to the small flash capacitor. The large one is approx. 2.5" tall. The smaller flash capacitor works fairly well and was used in Coilgun Mark I. The capacitor holds the power to run the coil.

This is your standard voltage meter which monitors the capacitor's charge as it charges up. It takes approx. 30 sec to charge it up to it's maximum of 200 volts. It is important to have the meter to make sure that the capacitor does not get more than 200 volts charge. Overloading it could cause it to explode, and I don't have any other big ones like this.

A relay is an electromagnetic switch. When it recieves power, it flips a switch inside to complete a circuit. In the Coilgun, it is used to connect power to the coil. I need a relay because I don't have any switches big enough to switch on and off 200 volts safely. The trigger connects 9 volts to the relay, which then switches on the 200 volts to the coil. In the image, the actual relay is covered in tape.

This is the barrel of the Coilgun. The projectile travles down the barrel. In my case, this is just a pen without the ink or top. Here is a closer view and a front-end view of the coil/barrel. In the front-end view, you can see the projectile sticking out the front of the barrel. The projectile can be anything that is attracted to a magnet, in my case a bit of a nail. The coil is what pulls the projectile and then releases it to go flying towards it's target. It is switched on and off by the relay. The entire 560 microfarads of the capacitor are drained through the coil in less than a tenth of a second, creating a high magnetic field for just a short time, long enough to accelerate the projectile to high speeds. Once the projectile has passed through the magnetic field, the field is shut off to prevent the projectile from being held on the coil or being pulled backwards.

Firing the gun consists of a few steps:

1. Insert projectile into barrel. Use stick to push to end
2. Turn on coil charger switch (located on front of camera)
3. Check meter. If charge is not increasing, check that firing switch is on "Hold" and that all connections are secure
4. Wait for charge up to 200 volts. Takes approx. 30 seconds
5. Flip firing switch to "Fire"
   --The Gun Fires
6. Turn charger switch to "Hold"
7. Flip firing switch to "Hold"
8. Flip meter through all DC settings to ensure capacitor is completely drained. Always flip back to 250 or 1000 volts when done

And then you're ready to do it again! That is, if you can find the projectile...

I don't really have any quantitative results. I know that this gun is fairly powerful for a single-staged accelerator. I can fire the nail straight through a piece of ordinary printer paper. It can punch small holes in cardstock, but not pass through it as it can with paper. If I could only find some way to measure it...
View the video of this thing shooting a hole in a piece of paper. And yes, that is my math book as a shield wall. It's not strong enough to punch through cardboard. Yet.

Well that's it! Hopefully I'll add some more stages to this gun, but I'll probably need a longer barrel. I assembled this completely from parts I found in my basement. Even that big capacitor was just sitting around. Try making your own! It's plenty of fun with an ordinary camera capacitor. Check out www.sixmhz.com and Wonko Labs for more in-depth information.