AC relays have a different magnetic core structure than DC so your idea will
not work. You could rectify the 120 to DC then use a resistor in series with
the coil to give 24DC at the coil. It would only require a diode, a
capacitor of a few mfd and a resistor. The whole thing could be quite small.
73, Dan. N5AR
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of Bob Maser
Sent: Thursday, December 23, 2004 7:12 AM
To: AMPS
Subject: [Amps] Relays
This may be a little off tune for the AMPS reflector but I need help(people
that know me have said that for years). I am converting an old Collins
20V-3 broadcast transmitter and I need a relay to do some power cutback
switching. I happen to have 2 really nice heavy duty relays made by P & B
but they have 24VDC coils and, since the Collins rig doesn't have anything
close to 24V, I would have to use a separate power supply just for these
relays. But then I noticed on the P & B data sheets that the coil
resistance and current draw are the same for a 24VDC relay coil and a 120VAC
relay coil. 288 ohms/84ma and 290 ohms/85ma respectively. Does this mean
that I can apply 120VAC to my 24VDC relay coil? How can this be? This
violates Ohms Law. I aint about to try this until I've checked with you
Elmers.
Bob, W6TR
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