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Relay question (adding relay to Oscars LED driver board) - it works!
JoyMonkey:
--- Quote from: RandyT on June 14, 2005, 04:48:36 pm ---Do you have a meter?
You should get continuity between the 2 coil leads.
RandyT
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Why didn't I think of that!!???
I checked and AB is closed, CD is open
So this means I've got it wired correctly, right? :o
SirPoonga:
Would it also be wise to put a diode across the switch of the relay to not allow feedback on that circuit?
I have to find my parallel port circuit again when I was looking at making my qbert knocker. There was a spike protection circuit on it because relays are notorious for creating spikes when triggered.
RandyT:
--- Quote from: SirPoonga on June 14, 2005, 05:03:59 pm ---Would it also be wise to put a diode across the switch of the relay to not allow feedback on that circuit?
I have to find my parallel port circuit again when I was looking at making my qbert knocker. There was a spike protection circuit on it because relays are notorious for creating spikes when triggered.
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That's what the diode is there for. IIRC, when power is removed from a coil, the magnetic field collapses and a spike can feed back and damage the circuit.
I think these are referred to as "snubbing" diodes.
(apologies to the EE types if I explained this wrong.)
If you were driving a solenoid (another coil) with the relay, a diode on the switched line would probably be a good idea to help protect the PC power supply. I don't think a CCFL is an inductive load, so it's probably not a problem here.
RandyT
SirPoonga:
Right, but I thought (I need to find that schematic) there was a diode or some sort of spike protection on the switch because when that switch is closed a spike can occur.
I know the diode across the coil is there to prtoect feedback from the coil.
Thinking about it, wouldn't a capacitor inline on the switched circuit supress spikes?
RandyT:
--- Quote from: SirPoonga on June 14, 2005, 05:18:02 pm ---Right, but I thought (I need to find that schematic) there was a diode or some sort of spike protection on the switch because when that switch is closed a spike can occur.
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That would probably be for inductive loads. I updated my post while you were typing ;)
RandyT