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Have a question about relays and the 12v trigger from my receiver.

post #1 of 13
Thread Starter 

I probably should have asked before buying anything but I bought this relay to switch on a 12v pc fan that is triggered by the receivers 12v trigger.

 

http://www.digikey.com/product-detail/en/1461069-5/PB1321-ND/3318145

 

That relay should work right? I did some reading and people recommend adding a diode (1N4001??) to prevent current from going back into the trigger. Is this right? If so, where would the diode connect to exactly? I'm new to all this so any help would be great!

 

 

So I found this image which I assume is correct.

http://www.bcae1.com/relays.htm

 


Edited by Mrkazador - 9/3/13 at 9:45pm
post #2 of 13
FWIW I've been using relays like that for years without any diodes. I haven't had any problems but YMMV.

Also, I find these worth the extra dollar to have the diodes, leds, and terminal blocks already on a circuit board. Before I used these I did exactly what your doing but I turn on my EP4000 with a DIY relay board.

EP4000 12V Trigger Mod.

Cheers!
Edited by NicksHitachi - 9/4/13 at 5:58am
post #3 of 13
Quote:
Originally Posted by Mrkazador View Post

So I found this image which I assume is correct.
http://www.bcae1.com/relays.htm


it is indeed correct.
the diode is there to protect the trigger circuit from reverse current when the relay coil magnetic field collapse.

normally an amp external trigger is already protected but if it weren't then the discharge will surely destroy it.
post #4 of 13
and also make sure the diode polarity is wired correctly.
the diode negative pole must be connected to the trigger positive output. reverse that and it will also destroy the trigger. smile.gif
post #5 of 13
Thread Starter 
post #6 of 13
Quote:
Originally Posted by Mrkazador View Post

This diode would work?
http://www.radioshack.com/product/index.jsp?productId=2036268

or one thats rated higher?
http://www.radioshack.com/product/index.jsp?productId=2036270
both should be fine, but since they're similarly priced get the 1N4004.
post #7 of 13
What are you using as your 12V power source? Will it just be running all the time? I'm just thinking it might make more sense to switch upstream of the source so that it's not running when the system is off.
post #8 of 13
Thread Starter 
I'll be using a 12v ac-dc wall wart which would be on all the time.
post #9 of 13
Thread Starter 

Another thing I just noticed. The mono 3.5mm plug I got is rated for 6vdc 1a... Is this going to be a problem? The relay draws 30ma if that helps.

post #10 of 13
Quote:
Originally Posted by Mrkazador View Post

Another thing I just noticed. The mono 3.5mm plug I got is rated for 6vdc 1a... Is this going to be a problem? The relay draws 30ma if that helps.
not gonna be a problem. with any plug (or any cable) its the power rating (voltage x current) that's more important than voltage or current alone.
the tip of the plug is usually the positive pole. if you have a multimeter confirm the polarity before wiring the diode.
post #11 of 13
Thread Starter 
Quote:
Originally Posted by paskal9 View Post


not gonna be a problem. with any plug (or any cable) its the power rating (voltage x current) that's more important than voltage or current alone.
the tip of the plug is usually the positive pole. if you have a multimeter confirm the polarity before wiring the diode.

 

Thanks, I will check polarity with a multi meter.

post #12 of 13
Thread Starter 

I finished building it and it works fine, thank you everyone for the help. I made this crude drawing so if anyone wants to build it

 

 

Parts I used from Digikey

CR282-ND - http://www.digikey.com/product-detail/en/09080-G/CR282-ND/250523

PB1321-ND - http://www.digikey.com/product-detail/en/1461069-5/PB1321-ND/3318145

CP3-1005-ND - http://www.digikey.com/product-detail/en/MP3-3501/CP3-1005-ND/992141

WM4201-ND - http://www.digikey.com/product-detail/en/0022232031/WM4201-ND/26669

 

and from Radioshack

1N4005 - http://www.radioshack.com/product/index.jsp?productId=2049728

post #13 of 13
Thats the DIY spirit son!
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AVS › AVS Forum › Audio › DIY Speakers and Subs › Have a question about relays and the 12v trigger from my receiver.