Determining the best relay

Thread Starter

primez

Joined Feb 10, 2016
4
Hello,

I am currently trying to wire aftermarket door lock actuators. The switch I want to use is a single wire. The switch is in a car, so it has a 12v source.

This is where it gets tricky - When the switch is pressed to "Unlock" it closes the circuit and has a resistance of 50 Ohms. The "Lock" side of it has a resistance of around 765 Ohms. My goal is to use relays to trigger 2 separate circuits.

The unlock switch will send the full 12v to a normally closed relay, in order to block the voltage to the "lock" side of it. The unlock pulse will also send the output signal to the door "unlock" mechanism.

However, for the "Lock" side of things, my idea is to use a smaller relay.. Perhaps a 3v or 6v. Something small enough that when the switch is set to "Lock" it is not quite powerful enough to trigger the 12v unlock because of the extra resistance. I am stumped here though because I am not sure whether or not this is the best solution and how to figure out the best way to wire the resistors and relay on the "Lock" side of the switch.


Any help or suggestions is greatly appreciated!
 

Thread Starter

primez

Joined Feb 10, 2016
4
It's one wire. I drew that to try to help show that it's a single output but with 2 different resistance values.
 

shortbus

Joined Sep 30, 2009
7,848
All car electric locks that I'm aware of, in use today, only use one motor for the door locks. The motor turns one direction to "lock" and reverses direction to "unlock". You do this with an H-bridge circuit. There are many H-bridge IC's (chips) that can be used to do this, no relays needed.
 

Thread Starter

primez

Joined Feb 10, 2016
4
Thank you for this. I think this is the info I needed but I had no idea what to call it so I had no idea what to even search! :D
 
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