Coil Gun [Part 3] – Testing the Boost Converter

I thought I would post a quick test I made of the boost converter circuit. In the video below, I’m charging the capacitor to a voltage of 200V. The charging takes about three seconds to go from the 15.8V (the initial voltage of the battery) to 200V, which is right within the ballpark of the simulations!

Here are some close up shots of the circuit board



Starting from the top left, I added in a push button between the regulated 9V output of the LM317 and the 555 timer. I realized in my original schematic that the instant I connected the battery it would start charging, which is definitely not what I want.

To the right of the push button is the LM317 voltage regulated which takes in 14.4V from a 4-cell LiPo battery and outputs a regulated 9V to power the 555 timer. The large ceramic capacitor and electrolytic capacitor are used for input/output filtering on the LM317. Two of the resistors are used to set the regulation point. In the middle of the board is the 555 timer, surrounding by the resistors and capacitors used to set the timing. The big guy on the right is the inductor. The MOSFET and diode are found at the bottom. I’ve also included an LED to indicate when the capacitor is being charged.

The two red and black leads coming out the top go to the 14.4V LiPo battery. The two leads on the bottom go to the capacitor.

If you want more information on this circuit, please visit this post where I cover the theory and design behind it. Next, I will be working on the firing circuit. Stay tuned!


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