Step 1 – Preparing the coils (DIY make coil gun without camera)

                                                  Making the coils for the coil gun

Take the PVC pipe and cut it , to get a length of 30-40cm. After that, take the insulation tape and wrap around the pipe from a distance of 1-2 inches from its end. Wrap the insulation tape above the pipe in succession until it reaches a thickness of 4-5 mm. Next do the same thing from a distance of 3-4 cm from the first wrapping.

Now take the copper wire and after leaving some slack on the beginning, start wrapping around the pipe, the wrappings are to be tight and close to each other with no gaps between them. After wrapping the first layer, cover it with insulation tape, then start wrapping on top of it for the second layer. The copper wires should be wrapped side to side in the same direction , either clockwise/anti clockwise. Repeat the process for 6-7 layers. 

For multiple coils, a spacing of 3 cm is required from the first coil . After preparing the coil, using sand paper sand the ends of the coil to remove the coating , to make them conducting.

Step 2- Making the capacitor charger

Camera flash circuitry and capacitors can also be used for this project, but since a large number of them are required, I found it easier to buy some high voltage capacitors and make a dedicated charger for them ; thus making a coil gun without a camera. To make the capacitor bank charger for the 400V, 3300uF capacitors, prepare a circuit as shown in the schematic :

                                            Coil gun charger circuit

Set up the bridge rectifier as shown in the schematic , I have used a 600V D3SBA60 bridge rectifier. After looking at the marking in the rectifier wire the ac pins of the chip to live and neutral lines of your AC supply. The + and – marked pins on the chip provide the DC voltage, the positive voltage passes through a 100W incandescent bulb , acting as a high load resistor, a switch is used to toggle on/off the charging of the capacitors. When using multiple capacitors, always choose them with the same rating and connect in parallel to increase the current supplied.

                                               Finished charger circuit setup

Step 3- Making the coil gun circuitry

                                                  Coil gun circuit

The coils on the coil gun have to be wired up based on the given schematic. Here an SCR (Silicon Controlled Rectifier) or thyristor is used to control the high voltage supplied to the coil, it acts like a switch. I am using a 50A rated stud type SCR , 50RIA120, smaller SCR’s like the TYN616 can also be used if 5 or 6 of them are connected in parallel as each provides a surge current rating of 200A. Conventional switches or relays cannot be used as it usually burns the contacts in them due to the high voltage and current.

                                                    Coil gun SCR

The working of an SCR is simple, when a voltage is applied to its gate via a small battery the diode is activated and the cathode and anode can be connected to the coil just like a normal diode. A switch that controls the gate voltage being applied to the SCR essentially controls the current going to the coil and acts as our trigger to the coil gun. 

Even if you are having a lot of capacitors hooked up in parallel , without an SCR capable of handling high current, you will not be able to supply the full power. High gauge copper wires should be used while connecting the capacitors and the coils. 

All connections and terminals should be properly insulated to prevent yourself from getting electrocuted accidentally. While choosing an SCR , choose one with a high value for “Surge Current/Itsm”, after checking its datasheet.

Step 4-Projectiles and testing of coil gun

                                                       Coil gun projectile

Here, any ferro-magnetic material based object can be used as a projectile, usually nails and bolts. I have found using bolts to be the most effective, due to the greater surface area at their heads.
The acceleration and distance travelled by the projectile depends on the projectile you choose, usually bolts of lengths at least equal to that of the coil are used. The spacing between the bolt and the coil is also critical, effective spacing between them can only be found out by placing it inside the pipe and testing the coilgun. The airgap between the projectile and the coil should also be minimal.The video showing the testing of a projectile :

Step 5- Putting it all together

                                                            Silicone Gun

In order to assemble all the components of the coilgun together which includes the coil and pipe, capacitors, SCR, switch, etc and to make the whole setup look like a gun I found a very easy way to do it. I was able to use a silicone gun ( a holding apparatus used for silicone adhesive tubes). I took apart all the parts which were not required such as the shaft, etc. But be careful while removing the spring as it is in high tension, remove it carefully as it could jump off from its holding and hit you.

Assemble the pipe along the length of the gun, fix it using some hot glue or other adhesives, arrange the SCR on the side and glue it. Tape the capacitor to the bottom of the gun and finally stick the trigger switch on the handle, wire the connections. Finally use some black spray paint to detail it. A low power magnet like those found in tiny speakers could be used at one end of the pipe , to hold the bolt or projectile in place, so that it doesn’t fall off while moving the coil gun. The finished coil gun :

Finished coil gun

This coil gun was extremely powerful, it smashed my window pane accidentally while testing it. It can pierce through foam, cardboard, etc. The video showing the coil gun in action: