I'm building a battery charger for my 60 volt ebike. I need a circuit that will shut off a relay when the voltage reaches just under 75 volts (around 73 if I remember correctly). I'd prefer some adjustment if possible. I'd prefer to avoid zener diodes if possible and use what I have available (assorted transistors capacitors resistors rectifier diodes etc.). The circuit can be powered by the battery bank or a separate 12v power supply (or even 120v rectified from a power outlet), the charger will spike to 160 volts when disconnected so using it to power the shutoff circuit isn't a good idea. My relay has a 12v coil