Crazy or unusual things around your home

Got something interesting to show the world? Then you've come to the right place! We all have something weird lying around so let's see it!

I built this, but sadly never quite got it to work before I got divorced and where I live now I'm arfaid to test cos if something went wrong and one or more parts went boom it'd likely scare the living shit out of my neighbors heh.

Is this a railgun? Lmao. Looks like rows of mosfets to toggle voltage on the rails. I assume then the circuit on top is a timer. Doesn't look like a 555 tho

@reisenpai66 Not quite, but you're close! It's a coil gun. Typically these use either high voltage caps triggered by a SCR (which is great for a high current, one-shot pulse like this) OR they use batteries with MOSFETs or IGBTs to send out a pulse. High voltage caps provide the advantage of a nice high voltage, high current pulse, but you only get one shot then have to wait a minute for it to charge. Batteries give you multiple shots, but typically at low voltage and low current. So I decided to try something much different and use Super Caps. This allows me to fire multiple times due to their high capacitance (3400 Farads!) and gives me high current, though it does suffer from low voltage. The ones shown are rated at 3400F, 2.85v. I only planned to go to 2.6-2.7v due to the fact that ESR (Equivalent Series Resistance) varies among caps and can result in caps connected in series ending up being charged to different voltages so I wanted a little room for error. I have 50 MOSFETs connected in parallel for switching on the power which goes through the 1" x 0.7" aluminum rails (I think the center rail is 1" x 0.85") and dual 4ga copper jumper cables. The timing chip used is a 74LS221 dual one-shot chip I happened to have lying around which trigger the other two chips which are H-bridge driver chips. They supply high current pulses to the MOSFETS because unlike BJTs, MOSFETs work by charging up their gate capacitors to turn on and you want to do that as quickly as possible to minimize the time during which the MOSFET is operating in the "active region" and consuming the most current and producing the most heat due to being partially on. There are power resistors to discharge the MOSFETs when the power to their gates is turned off. The rest of the parts are for voltage regulation. The tubing and clamps are made of Acetal Delron for a good combination of durability and low friction. The coil is 10ga copper wire since due to the low-voltage I needed to keep the resistance very low to allow me to use the high current output of the super caps. So to do that, I couldn't use many windings anyway so I wanted to use as thick of wire as possible that I would still be able to wind a coil from so 10ga seemed like a good size. I thought about 8ga, but I was worried it might not bend well enough so I went with 10ga. I planned on the current output to be around 1,700 A. Oh, and that massive hockey puck diode I'm using as my flyback diode is rated at 700V and I think 2,050A. Not too shabby :) The parts were all machined using a manual mini-mill I bought from Little Machine Shop. I hand to hand-tap over 100 holes, mostly for the MOSFET heatsinks. I built the flyback diode clamp. The firing tube clamp was milled too. It was a LOT of effort but I enjoyed it. Sadly I won't be doing anything like this again anytime soon cos I had to sell my mill and my bandsaw (a nice freestanding 12" Craftsman one) during my divorce for much needed funds at the time plus I don't have a place to do any milling or sawing at my current apt. anyways. But sadly it didn't work. As to why I think it didn't work.... The problem is I wanted to use the caps to power the control circuitry too, but when the voltage drop produced when the coil is switched on makes the circuit goes crazy and lock up for some reason so I need to just use lead-acid batteries to supply the high current needed for the MOSFETs instead, do some circuit tweaking, and it should work. Keyword: should. If something went horribly wrong and a part went boom it would likely scare the living shit out of the neighbors heh, so I don't want to work on it here. Someday I will again, but it's gonna be awhile till that happens. FUN FACT: When I first tested it, and it locked up, the coil was left on and kinda sorta heated up rather quickly. The insulation caught fire heh, and it actually MELTED the 10ga copper at one point which requires I think 1983 degrees F. The firing tube was melted too needless to say though surprisingly the clamps were a bit discolored and needed sanded some, but relatively unharmed. So I did that and put in a new tube and it's good to use if I ever move somewhere safe to work on it again heh.

>3400F holy hell. I remember back in school when my teachers had a super cap that they had to short with a resistor just so it doesnt pull current from the air lol.. Also yea i knew they were mosfets mainly based off possible application of them. Ive seen mosfets also used for timing.. if you need precision timing that it.. its good for hardware glitching. But yea, fun stuff.