Homemade dive torch

Hi all
I am putting together a dive canister torch. I want to build in a auto off capability in the circuit. The torch head will join the canister via a e/o connector. If the canister power is on but the torch head is not connected I want to have a circuit that will break and not send power to the e/o connector. This will prevent corrosion if I am changing light heads underwater or using the canister to power other devices. What is the best way to do this? A automatic reset circuit breaker or is there another way?
Thanks
Brian

If you could use three wires, you could keep a constant low voltage on one pin, then when the light head is connected, it would ground that pin and cause the canister to turn on the power. This would reduce but not eliminate galvanic corrosion.

The only way I can think to do it with two wires is to use a microprocessor to periodically turn it on, sense the load, and if there's no heavy load, turn back off. You could conceivably do that at a lower voltage than your main battery pack, to further reduce corrosion.

Can't you just turn off the canister?

Thanks for the reply. I think I am going to go the simple route with a on off switch.