RE: [CAD_CAM_EDM_DRO] Relay question about diodes across the coil

Normally diodes are used acrros DC relay coils - the main reason is
to stop back emf and prevent the inductance of the relay coil
creating spikes etc . Its good standard practice.

-----Original Message-----
From: washcomp [mailto:jeff@...]
Sent: 11 January 2004 02:06
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Relay question about diodes across the coil


Back when I was a kid learning about relay circuits on the job
(1960's), most of the control circuits I got involved in used low
voltage A.C. and I don't ever remember seeing a diode. I just found
out that it's good practice to put a diode across the coil of relays
to keep them from chattering due to the current stored in the coil
inductance. Question is: Only on D.C. relays or is this supposed
to be done on A.C. relays as well?

Jeff




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