"Bob AZ" wrote in message
oups.com...
On Aug 22, 7:49?pm, "Steve W." wrote:
Looking for a way to activate a small lamp to show when a remote mounted
water pump is running. I know I have seen the method before but my dusty
brain cannot seem to find it. The pump is a 120volt unit mounted in a
remote pump house out of visual range or I would wire a light across the
pressure switch. I was thinking of something like an inductive coil
around the hot lead feeding a circuit that would power the light. No
problem working on the panel end. Ideas?

--
Steve W.

Steve

Perhaps a current meter is called for. And I am sure there are current
sensing relays that would light a bulb. Also a pair of wires from the
remote pump house would be a way. I am sure there are other solutions.

Bob AZ

I have seen it done using a small current transformer made by feeding the
cable through a ferrite ring, and winding a few extra turns of thin wire on
there, which is then fed to a little opamp circuit, the output of which, you
can do what you like with - feed a relay, switch a bulb, switch a little
license-exempt transmitter, and so on. I'm pretty sure that Elektor magazine
did a circuit like this as a project not so long back. You could try
searching the archive on their website at www.elektor-electronics.com

Also, I think that you can get ready made units for control of computer
peripherals. You just plug your computer in through it, and when it detects
that the primary load - your computer - is drawing current, it switches
power to auxilliary devices like your printer. Subbing the pump for the
computer, and using one of its switched aux outputs to drive a relay or
whatever, should work. Also, simplest way perhaps, connect a wall wart power
supply across the pump feed. Then when the pump comes on, you will have a
low voltage of any value you choose, available to do what you like with. If
you can't get wires easily to where you need to know that the pump is
running, then a wireless link is probably going to be best. You can get all
sorts of ready built modules for transmit and receive now. The ranges, and
directivity, can be extended considerably, by adding home brew external
antennas.

Arfa