Author Topic: Relays with Capacitors  (Read 2599 times)

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Offline airman00Topic starter

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Relays with Capacitors
« on: July 13, 2007, 02:57:05 PM »
I have 4 DPDT relays and when I switch them on sometimes they do not remain closed. I don't have any capacitor on the relay coil contacts.
How should I put the capacitor on the relay, and is there maybe another problem why the relay contacts dont close.
The relay runs on 2 AA batteries and switches 6 volts @ 1 amp.


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Offline Del

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Re: Relays with Capacitors
« Reply #1 on: July 13, 2007, 04:11:31 PM »


2 AA's provide about 3V. I think most relays need at least 5V.
It should say on the relays how many volts they require to stay on.
Do the relays work better when you apply a higher voltage?


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Re: Relays with Capacitors
« Reply #2 on: July 13, 2007, 04:38:08 PM »

 Does your relay just not open at all sometimes or can you hear it clicking a lot as it continuously opens and closes?

 Its not 100% necessarry to use a capacitor on a relay, although it can help with decoupling/ smoothing signal.
 If youre using the same batteries for the relay coil as the circuit,then when the relay switch closes, the circuit may drain the batteries too much and therefore open the relay again.
 Also check the batteries / required ratings etc...
 Also youre relays could be damaged if the coils have over heated due to over powering them...


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