Reverse polarity 12v DC automotive use

[capofarukgb]

Good evenings, it's probably very easy but I can not get my head around it, I am trying to mimic what is normally achieved through a mechanical Relay, reversing a trigger polarity from hot 12v + to negative ground.
Currently achieved this by using as said before spdt mechanical relay 12v 2amp, 86 + 12v trigger, 30 and 85 ground negative 87 is my negative output.
Excellent job done !! Not really, Im not a fan of mechanical relays, and want to change to solid state type, SSR are expensive, so since what I am trying achieve is simple, I wonder any of you have another method using ICs or etc, as long it's cheap and smaller than normal hella relay.
The image is what I have installed
Thanks in advance guys

 

[dougy83]

use this

 

[capofarukgb]

use this **broken link removed**

Dougy ty, I presume the input is a 12v +, also would you be able help with the values of the components, I'm totally out of touch lol thanks

 

[dougy83]

Yes, 12V is +ve. The earth symbol is the chassis/negative. I'm not sure of the current requirement of the trigger input of the PDM60, but I'm assuming it's quite small, therefore a small signal transistor e.g. BC548, 2N2222, etc. should be acceptable. The diode can be 1N4148, and is likely optional (only required if PDM60 input is internally a relay coil). I've updated the schematic to reflect these details.

 

[capofarukgb]

Yes, 12V is +ve. The earth symbol is the chassis/negative. I'm not sure of the current requirement of the trigger input of the PDM60, but I'm assuming it's quite small, therefore a small signal transistor e.g. BC548, 2N2222, etc. should be acceptable. The diode can be 1N4148, and is likely optional (only required if PDM60 input is internally a relay coil). I've updated the schematic to reflect these details.

Thanks buddy the PDM 60 actually only requires a negative ground tigger on the BLUE wire the relay actually doesn't have any other connection to the PDM, I take it the OUT from the collector can go straight to the blue wire ? And this would be a negative ground when the circuit is active ? Thanks again

 

[dougy83]

I was saying that I don't know what is inside the PDM60, e.g. it could have a relay inside that connects to the blue wire. I think it's unlikely though.

Yes, the circuit will output a "ground" (or close to) signal when you input a voltage >~6V. The output connects to the blue wire.