I've been working on a silly gadget using the cut & paste bits of other circuits technique combined with a large does of ignorance :-).
The gadget details can be found here:
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With my breadboarded circuit, I have been observing a phenomena that my tiny little brain can't figure out.
When I expose the cadmium sulphide photoresistor to light, my relay triggers once (briefly) as expected and desired.
However, fairly often (not all the time), when I put the lens cap back over the resistor and block off the light, the circuit will trigger the relay again.
The only theory I have (with no access to a scope that can record whats happening at different points and show me) is that the photoresistor resistance actually bounces around some as it gets dark rather than simply smoothly going back up. Could that be it? Or has the ignorance part of my design process merely led me to do something silly along the way?
Any ideas for improvements to my design or explainations of this puzzling behavior gratefully accepted. (I doubt it is gravity waves though :-).
(Perhaps chuck the whole thing and detect incoming calls via the headset interface is a better plan - but I'd have to find out about interfacing to cell phone headsets for that to work...).