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wiring spdt relay with multiple accessories


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rocgalant 
Member - Posts: 13
Member spacespace
Joined: February 07, 2009
Location: Pennsylvania, United States
Posted: March 18, 2009 at 11:11 AM / IP Logged  

Hello. I have a currently have my amp turn-on, Ipod charger (it's an A/V to Ipod dock connector w/ charging), and FM Modulator spliced to my radio's turn-on wire. I have been reading that a relay is much safer so I want to do that. The diagram 'connecting additional devices to the remote turn on wire' is pretty straightforward. I'm just confused to how I wire points 86 (remote turn on) and 87 (constant 12v +).

1. For 86, do I splice into my radio's turn on wire? Or cut the remote wire; wire it directly to the relay, then connect the remote wire that is still attached to the radio, to point 30?

2. For 87, can I splice into my radio's constant 12v+ with a fuse? Or do I have to get the 12v+ directly from the battery?

I appreciate any help.

P.S. I looked around and found that the Ipod can draw up to 500ma when scanning songs. The amp turn-on, and fm mod would draw up to 100ma max; so I figured the combined draw of all connections would be under 1a. Go with a 1a SPDT micro relay?

KPierson 
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Location: Ohio, United States
Posted: March 18, 2009 at 12:37 PM / IP Logged  

I would use a standard 30A automotive relay.

The remote out from the radio would ONLY go to the (+) coil (pin 86).  You could use the main 12vdc from the radio at pin 87 but you should fuse it down to a max of 5A or so. 

Kevin Pierson
rocgalant 
Member - Posts: 13
Member spacespace
Joined: February 07, 2009
Location: Pennsylvania, United States
Posted: March 18, 2009 at 12:56 PM / IP Logged  

Thanks! So I think I follow regarding pin 87- splice the constant 12v+ wire from the radio and put a 5a fuse between the relay and wire.

I'm still confused though on pin 86. Can you paraphrase the term 'radio out'? The way I understand it, the radio harness only has a remote in (the radio receives the input signal from the remote wire telling it to turn-on). Is there a separate out wire that I should be looking for or am I just way off here?

soundnsecurity 
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Posted: March 18, 2009 at 1:07 PM / IP Logged  
rocgalant wrote:

Hello. I have a currently have my amp turn-on, Ipod charger (it's an A/V to Ipod dock connector w/ charging), and FM Modulator spliced to my radio's turn-on wire. I have been reading that a relay is much safer so I want to do that. The diagram 'connecting additional devices to the remote turn on wire' is pretty straightforward. I'm just confused to how I wire points 86 (remote turn on) and 87 (constant 12v +).

1. For 86, do I splice into my radio's turn on wire? Or cut the remote wire; wire it directly to the relay, then connect the remote wire that is still attached to the radio, to point 30?

2. For 87, can I splice into my radio's constant 12v+ with a fuse? Or do I have to get the 12v+ directly from the battery?

I appreciate any help.

P.S. I looked around and found that the Ipod can draw up to 500ma when scanning songs. The amp turn-on, and fm mod would draw up to 100ma max; so I figured the combined draw of all connections would be under 1a. Go with a 1a SPDT micro relay?

take your remote wire from the radio and hook that to 86. doesn't matter whether you splice into it or run the wire in and out with a connector.
run your 85 to ground
run your 30 to a 12v constant source ( cig lighter, radio constant, whatever you can find. also it would be a good idea to be to put a 1 amp fuse on this wire.
run your 87 to whatever you want to turn on. if you add more devices later you should upgrade the 1 amp fuse.
KPierson 
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Platinum spaceThis member consistently provides reliable informationspace
Joined: April 14, 2005
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Posted: March 18, 2009 at 3:44 PM / IP Logged  
rocgalant wrote:

Thanks! So I think I follow regarding pin 87- splice the constant 12v+ wire from the radio and put a 5a fuse between the relay and wire.

I'm still confused though on pin 86. Can you paraphrase the term 'radio out'? The way I understand it, the radio harness only has a remote in (the radio receives the input signal from the remote wire telling it to turn-on). Is there a separate out wire that I should be looking for or am I just way off here?

The radio has a switched power lead (the red wire) that tells it when to turn on.  It then has a remote turn on output (usually blue or blue/white) that tells other devices to turn on.  This output is what you want.  The relay coil should be the only thing connected to this wire.

Kevin Pierson
rocgalant 
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Member spacespace
Joined: February 07, 2009
Location: Pennsylvania, United States
Posted: March 18, 2009 at 7:33 PM / IP Logged  
Fantastic! Thanks again for your help. I would have been lost without the info.
rocgalant 
Member - Posts: 13
Member spacespace
Joined: February 07, 2009
Location: Pennsylvania, United States
Posted: March 23, 2009 at 10:43 AM / IP Logged  

Ok last question. So I am trying to get a SPDT and of course, it's not available in my area. I tried auto shops, electronics shops, general wholesalers, home improvement stores...nothing. So I was wondering if I could use a SPST 30a relay instead? Would that basically mean that whatever is wired to it, will always stay on since there is no 87a (Normally Closed) contact for the relay to rest at?

https://www.the12volt.com/relays/page5.asp#rtol

rocgalant 
Member - Posts: 13
Member spacespace
Joined: February 07, 2009
Location: Pennsylvania, United States
Posted: March 23, 2009 at 11:18 AM / IP Logged  

Sorry about multiple posts. Just wanted to give an example- So if I wire an Ipod charger (approx 1a), FM Modulator (2a), and Amp remote turn (under 1a) on to a SPST relay, would those accessories continue to draw power from my battery even when the car if off? Would I have to install a switch?

soundnsecurity 
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Gold spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: November 10, 2008
Location: Louisiana, United States
Posted: March 23, 2009 at 11:37 AM / IP Logged  
it would work, because even though there is no normally closed the other post isnt on all the time. that would defeat the purpose of having the relay in the first place.
rocgalant 
Member - Posts: 13
Member spacespace
Joined: February 07, 2009
Location: Pennsylvania, United States
Posted: March 23, 2009 at 1:51 PM / IP Logged  
So pin 86 (the remote turn on wire) would serve the same purpose as having a 87a (NC)? Pin 86 will tell the relay when to 'activate?'
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