ORIGINAL: zcacogp
Just thinking about it ... if you were to wire a sounder..............
Yes think about it a bit more Oli. I don't mean to ridicule, but where on earth is the earth return to provide the potental difference? With a diode in circuit, with the ignition on, either the ignition feed or the light feed will be a dead short, or the buzzer will permanently sound with the lights on; without the earth there will be no voltage across the sounder surely?
A normally closed relay fed from the side-light circuit, feeding the sounder, would give a permanent signal if the lights are on, but by enabling it via the ignition supply the relay will drop out silencing the sounder all the time the lights are on. Lights off, no supply, ignition off, relay closes but the supply has been interrupted.
If you need, and absolutely must have a sounder that is. I know this my be contentious, but I reckon people who need this sort of device are incompetent by defintion and should not be left in charge of a hot sewing machine, in my humble opinion.
In answer to the next question, yes once. Since then I turn the engine on before anything else, and swtich everything off before killing the engine.
You watch I bet I leave my lights on tomorrow.