I want to sense pressure in a line that feeds part clamps and turn on a
green light and/or have a red light go out so the operator will try to
remember to clamp the parts. (don't laugh) I could use a compressor switch
for about $30 and a search finds sensors for about $80. Can I use an
automotive oil pressure idiot light switch or something like those? They
are only $5-$10. Any other ideas?