[guitaniac]

benmandv,

I believe that you need a stereo jack with three contact tabs (four total contacts, including the ground contact) to do this right. The battery lead is wired to the longest contact tab (the shortest tab being the tip contact and the medium length tab being the ring contact). When a plug is in the jack, the long contact tab is shorted to ground and the power circuit is completed. When no plug is in the jack, the power circuit is open and the battery is conserved.

If you have a stereo jack with only two contact tabs (tip and ring), and you've wired the battery lead to ground, then the power circuit will be on constantly unless you remove the battery when the pickup isn't being used (or you insert a switch of some kind into the battery circuit).

I cases where you're wiring a single active pickup system to a stereo jack, the ring contact can act as the switch contact (presuming that you'll be inserting a mono plug into the jack).

Hope that helps,
Gary