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Simple relay question..

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Swifty

New Member
Hi,

I have a sound activated relay circuit, I would like to use this circuit to break the connection to a set of speakers from a stereo unit.
I need:
A relay on the speaker line that is always making a connection when no power is applied (so that the speakers are working)
Then when a signal is detected on the sound activated relay circuit, the relay on that circuit will send voltage to the relay in the speaker line, which should then switch and break the connection (so no speaker output)
Can I do this ?
Is there any special relay i need / how do i wire it up ?

Many Thanks ;)
 

Exo

Active Member
Just use a Normally closed relay. It will disconnect when power is applied.

Try to find a REED relay that can handle the power to your speakers. Reed relay's contacts stay clean for longer, ensuring good connection.
 

Swifty

New Member
Thanks for your quick reply :)
I have just been looking on www.maplin.co.uk but none of the relays on their site seem to state whether they are NC or NO, is there also another term used?
I someone could give me a part no from a UK supplier I would be very thankful :D
It will be running 12V and the speakers are std fit car speakers.

Thanks
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Swifty said:
Thanks for your quick reply :)
I have just been looking on www.maplin.co.uk but none of the relays on their site seem to state whether they are NC or NO, is there also another term used?

They are usually described like this:

SPCO - single pole change over
DPCO - douple pole change over
SPNO - single pole normally open
DPNC - double pole normally closed

I'm sure you can work the rest out from that.

The details are stated in the Maplin catalogue, and presumably on their website.

You will need either a DPNC, or two SPNC (for stereo), or you could use DPCO or two SPCO, using the normally closed contacts.
 

nettron1000

New Member
The sound activated relay will work assuming the sound detector is in a location that will not detect sound from the speakers themselves.
 

Swifty

New Member
Thanks for the info guys ;)

Just to check so I don't kill anything :D would the 12v version here be ok ?
**broken link removed**

I would need 2x DP because I want to control 4 speakers, is that correct ?

Lastly, I presume with ChangeOver relays, you simply fix the wires to opposite ends depending on whether you want it NC or NO ?

Many Thanks :)

Neil
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Swifty said:
Thanks for the info guys ;)

Just to check so I don't kill anything :D would the 12v version here be ok ?
**broken link removed**

Yes.

I would need 2x DP because I want to control 4 speakers, is that correct ?

Yes.

Lastly, I presume with ChangeOver relays, you simply fix the wires to opposite ends depending on whether you want it NC or NO ?

You fix one connection to the common, and the other connection to either NC or NO - whichever you want, in your case NC. Where the actual contacts are depends on the particular relay, they are usually marked.
 

mozikluv

New Member
relay

:D hi

just would like to know if your amp where your speaker is connected is being used, when the sound activated relay kicks in?
 

mozikluv

New Member
relay

:D

so what is the substitute load of your amp when it is disconnected from the speaker, or does the amp automatically turned off when it is disconnected from the speaker. :?
 
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