Disclaimer: You should only use this for self-defense purposes and not for offensive acts. Especially don’t use it on friendly animals like pets, that’s just messed up. I am not responsible for vigilante use either (you know its awesome, but still illegal). You can test it on yourself just to see if it works if you want to though… MAKE AT YOUR OWN RISK!
For Input, You can use 3.7 volts any battery like mobile battery/18650 Battery or you can use 2 AA or AAA 1.5volt Battery in series. if you use 3volt as input change 470-ohm resister with a 220-ohm resistor