To remember the bistable state since the last power down - a carpenter relay is the simplest.Here's one for the transistor gurus!
I've got a BJT flip flop circuit I've been playing with....2 NPNs, and 2 PNPs. The PNPs are driving 2 LEDs. Nothing fancy.
This is so my father in law (the railroad buff!) can switch tracks using a DPDT toggle (center off), and have an indicator light for which way the tracks are now set.
Ok, doing this is easy. BUT - REMEMBERING which light should start "ON' - that is not so easy! There is no electrical connection between the switch machine or tracks and this circuit. I'm thinking I may HAVE to provide one or this may prove impossible.
Any suggestions on how to force one LED to be high at power-up?
Thanks!
Alternatively - a CMOS bistable with a lithium coin cell backup battery.