The CoilGun MK.II Project
CoilGun MK.II
Later on with another friend, Peppe, we initiated another coilgun project. We started studying the topics we needed to create a functioning coilgun, starting from electromagnetism to power electronics and C++ programming. Then I bought a 3D printer that made the prototyping much more easier than before. A little bit of thinkering and we came up with the Coilgun MK.II.
This iteration was the first one that actually worked and didn't just made us waste money.
Overall
This design is almost full modular, expect some parts that are glued togheter. We used an Arduino Nano as the brain, controlling everything from the firing routine to the sensing of the bullet. The firing tecnique was changed, from a manual timed firing routine to an automated one, using IR led and IR receiver positioned at the end of every stage.
The MK.II had 4 stages and each one of them had 2 capacitors in parallel, specifically 400V@1500μF ItelCond capacitors, coming to a total of 400V@3000μF. We also added for each stage's coil a flyback diode in anti-parallel to preserve and protect the semiconductors used to switch the capacitors. To charge up these capacitors I built a very simple boost converter that, while being highly inefficient, helped us with the charging of a total of 8 capacitors. At the end of each stage there were an IR led and an IR receiver used to sense the passing of the bullet, this way we could turn off the current stage and trigger the next one.
To switch the capacitors on the coils we started using N-Channel Mosfets; unfortunatly they've all blown up because of the high power generated by the capacitors. The solution was found in the SCR. We designed the circuit to drive the SCRs and ordered the corrisponding PCBs from JLCPCB. Each PCB had an octocoupler to isolate the low voltage arduino side from the high voltage capacitors side.
The bullet used was a headless 4.5 mm steel nail, weighting ~5g and long ~4cm.
Here you can see the coilgun penetrating a soda can.
Features
- Arduino Nano as the MCU
- 4 Stages, each one with 2x 400V@1500μF capacitors in parallel
- SCRs with IR sensors as the automated firing tecnique
- Boost converter to charge up the capacitor bank
- Efficency unkown