In a recent post on another thread I said that all you needed for a boot light switch was a miniature PIR and a 3v relay. JJ asked for details. As I had the bits I said I would build him one.
I normally draw a circuit and breadboard the circuit when I start a job but as there was only two components I didn’t bother, I just soldered it on a bit of vero board. Tested it and it didn’t work. Hme.....
I put 3v across the relay coil and it clicked in OK. 5v across the PIR and the correct 3.5 volt output, so why wouldn’t it work. On to google, the specs of the component said it should work. Then I realised the bits were built of Chinesium. When I checked the output voltage of the PIR with the relay coil in circuit the output of the PIR dropped to near zero. It seems that not all components give the rated output.
Solution. Design a better circuit. I’ve drawn the circuit but as it’s in pencil it won’t photograph, so tomorrow I’ll draw it a bit better, photograph it and post it.