It's not that I'm paranoid about the security of the cupboard. As I stated in the original / first post, the cupboard contains general household items (used once or twice daily). I have given the key to the missus ... who always misplaces it and then there's a search operation in 3 rooms of the house to find it.You will need to consider, the person could just hold the door open.
If its something that is ok to access by the person at home your sending the unlock code to, then there is really no reason to just not install a normal lock and give that person a key?
Its a fun project and all I guess but not very functional, and not very secure at that.
Those latch style locks are easily bypassed with a thin plastic shim. The problem with bolt latches tho is the door needs to be shut before it can lock.
Wait ... I think I can make a complete comedy serial based on the concept
Back to topic: now to find a suitable amplifier (if sound amps are not to be used), then decide whether to use the vibrator motor connection for pure dc or rectify the ringing signal. The rectifier part is easy. 4 diodes and it's done.
How can I build a suitable amplifier for it? Any help?