I love the idea of pillories, stocks an fiddles, but I wonder what damage would be done to the neck of someone in a pillory if they passed out, or in a fiddle and they fell over.
As for designing a lock, here's an outline of my suggestion. I know you will all say “too complicated”, but I've already drawn the diagram so there's nothing lost by posting it. It might give someone an idea. It is both an emergency release and a lock. The emergency release is based on my suggestion at
http://forum.boundanna.net/board/viewto ... 9&start=60 so please read that first.
In this case the
micro SD card (about 1/2 inch long ad 3/8 inch wide) is used as a latch. The top diagram shows a section through the locking device, which in built into one half of the fiddle. The bottom diagram shows the top. The fiddle is locked by moving the lever so as to engage the catch with a screw in the other half. You must arrange things so that you can both open and close the lock with your hands in the fiddle and the handle must be properly fixed. If it falls off you might be stuck! If you decide to make the fiddle to go round your neck, you would need an elastic loop so that you can close the fiddle around your neck then fasten it closed with the elastic. This should allow enough give to wriggle your hands in. With the relay energised, you then lock the fiddle with the lever, the SD card will be pushed down by the bevel on the latch and spring up behind it. You can still open the fiddle, but you will have to break the micro SD card, with the consequences discussed in the other post. When the relay is not energised, the SD card can drop and you can open the latch without breaking the card. Then you can put the card into your computer, recover the combination and open your safe.
The relay could be energised by a timer but, for a fiddle, it might be simpler to just have a battery built into the fiddle. The relay will open when the battery goes flat. You could use a rechargable of the right capacity to give you the maximum time you need. You need not have a fully charged battery for shorter times.
You could use an electromagnet and a piece of metal instead of the relay.