Simplest magnetic thing I can think of is a latching hall chip. One pole of a magnet turns it on, and it stays on until it sees the other pole (I forget if N or S turns it on or off.) Downside is that it always pulls a little power to keep the chip running.
Can you use a reed switch? Put a magnet nearby to turn it on, remove the magnet to turn off. No extra power drain with this.
I don't like the latching reed relay idea - balancing a coil's field to match a magnet's field looks like trouble.
Post by jimustanguitar on Mar 24, 2014 7:43:24 GMT -5
Semi off-topic, but talking about the reed switch reminded me of a funny story.
The auto turn signal cancel on most '80s era Yamaha's had a rotating magnet in the gauge cluster attached to the speedo cable. It would trigger a reed switch in a little glass tube that would kick off the relay when the frequency got high enough...
The funny part, and why this is worth retelling the story, is that since the reed switch was in a little glass tube, and it was green tinted for some reason and glued behind the gauge face, everyone thought it was a burnt out gauge cluster light and many a mechanic has searched Mouser and Digikey for a replacement 'bulb'
Last Edit: Mar 24, 2014 7:43:56 GMT -5 by jimustanguitar