Water Rifle

LTSpice Design

• I decided to download and learn LTSpice to simulate my inverter design - a push pull drive inverter made from an old power supply. It took me a while to get the center tap drive to work correctly as I modeled the transformer with inductances that were far to small ( i was thinking of SMPS inductors when i picked the simulation values ) when what I have is actually a big iron core transformer with way bigger inductances - which caused issues with the sim. (claude helped me realize my mistake, i was grasping at straws) but after I adressed that, it worked great and i decided to adress the voltage spike and ripple dampening - a 33V TVS diode and an RC snubber are necessary to protect the transistors from the spikes generated by the switching of the transformer (55V to my 60V rated transistor). The simulation performs as expected which i’m quite happy with!

• Claude was previously used to figure out estimated ratings for some obscure old bipolar transistors I have that I am using in the inverter.

• The first two screenshots are the collector voltages without and with RC snubber and TVS diode ( big difference ) the third screenshot is a general analysis on the power levels in the circuit (primary and secondary voltages + current draws)

It’s glorious, it’s dumb, it’s an overengineered water gun built from junk.

• I actually started this early this summer and now decided to submit it to stardance so other people could check it out and possibly build it (and so i can get some funding to upgrade it as i’m a broke student)
  The watergun uses a compressed air tank to provide the energy for the water to be shot and uses a solenoid valve to precisely shoot only a little water (making “bullets”)
  It uses an expresso pump to repressurize the accumulator chamber so that the air chamber doesn’t need replenishing.