HIGH VOLTAGE SAFETY: This device uses a modified circuit that provides 600V at a maximum short circuit current of 15 mA. Although the bulk storage capacitor that holds a large amount of charge must be removed to use this circuit with the counter (removing a big safety issue), it is still dangerous. Use gloves when working on the circuit after it has been turned on. Discharge all capacitors, as even the small ones onboard can give you a painful zap. Be sure to ground your case (if you use a metal one) so that if the high voltage accidentally touches the case it will simply short instead of turning the entire case into a live +600V terminal.
I forgot to ask... Are you still alive, or did your earbuds electrocute your brain? Don't bother replying if you're dead. I'll get the message. B-)