You may want to look into Hall Effect switches. You would be amazed at how many places they are used and their accuracy. They have three connectors - +v, -v, output. For my G540 I connected them directly to my 24v psu and the output directly to the G540 - works like a charm! Accuracy is a smaller number than I can measure with the equipment I have - a .001 dial indicator. The hardest part is getting your magnets aligned to where you want them. The other nice thing about them is the cost - $2.30 from DigiKey - p/n US5881LUA-ND. The magnets you can get just about anywhere, I salvaged mine from some cheap, $1.00, wooden boxes from a Michaels craft store - 2 magnets per box!
Gary |