Hooking up a relay and need help. (I must be slow)

[Nico Koutouzis 10+ year member]

Anyays, I bought an automotive relay 30A from radioshack and an N0001 diode. If I use my accessory plug for the remote line do I still need the diode? If I use the remote line from my HU where do I solder the diode. Its a 4 pin relay so it would help if someone told me what goes to what. (ground, +12v, Remote Line, and the wire to power my accessories). PLEASE HELPP

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[daboyfrumdabx 10+ year member]

85-Your remote wire

86-ground

30-12v

87-to the accessories.

Not sure what you need a diode for...

 

[Nico Koutouzis 10+ year member]

thanks man. they said u need a diode so u dont burn out the transistor in ur HU. Im just going to hook it up to the accesory line and be done with it. thanks again

 

[daboyfrumdabx 10+ year member]

Yeh, I'd say you'll be fine without it. If you want to, it would go on that remote wire, but I don't see issues arising.

 

[bubbagumper6 5,000+ posts]

Check this: Relay Diagrams - Quick Reference

 

[keep_hope_alive Premium Member]

from:

Relays

Quenching Diodes:Anytime that a relay coil is driven by a circuit that is not specifically designed to drive a relay, you should use a quenching/suppression diode connected in parallel with the relay coil. The diagram below will show the connection of the diode. Initially, you may think the diode serves no purpose because the voltage applied to the relay cannot pass through the diode. This is true when the relay is energized. The diode comes into play when the power source is removed from the relay coil. When power is applied to the relay coil, a magnetic field is created and energy is stored in the coil. When power is removed, the magnetic field collapses causing a reverse voltage to be generated (it's called inductive kickback or back EMF). The back EMF can easily reach 200 volts. The diode will absorb the reverse voltage spike. This voltage, if not absorbed by the diode, will cause premature failure of switch contacts and may cause the failure of power switching transistors. You can use virtually any type of rectifier or switching diode (i.e. 1N4001, 1N4002, 1N400x... or Radio Shack part #s 276-1101, 276-1102, 276-1103, 276-1104).

you can see a wiring diagram in the link above.

i was starting to type a similar answer, then remembered bcae1 has it already.

 

[maylar 10+ year member]

The diode goes across the relay coil, cathode side (banded end) on the plus (where your HU remote would also connect).