Tom Gardner wrote:
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?



What pressure. There are A/C system switches as well as oil pressure
switches and even brake light switches that operate using brake
pressure. The OP idiot light switches usually turn OFF (NC contacts) at
about 5-8 PSI. The A/C switches depend on which end of the system they
are on. The high pressure switches usually turn on about 120-140 PSI
(and there are adjustable ones)
The brake pressure light switches turn on around 100-150 PSI. (Ford,
Chrysler)

--
Steve W.