ORTATTW switch and dimmers

Hey - I searched, but wasn't able to find the answer to this question :

I have an ORTATTW switch - and getting it to light up is easy enough. However, if I tie it to the dimmer circuit, it works backwards. Dimming the lights makes the switch brighter, and vice versa.

So, how can I make the ORATTAW switch work correctly with the stock dimmer ?

 

No idea! Maybe reverse the wires?

 

Ok, thinking about this - the stock switches must ground through the dimmer.

Green wire = hot when lights on. White/green = 0(on) to 12v(dimmed).

So, if I ground the switch to White/green, it would work.

However, the ORATTW switches have a common ground for the switch and the lights. So, I can't ground to White/Green or bad things will happen. Therefore, I don't think it is possible to have this switch be dimmed.

 

So, not content to not have dimmed aftermarket switches, I designed a simple difference amplifier circuit.

Input 1 is the 12v lighting circuit. Input 2 is the variable 0-12v lighting circuit (dimmer). The output is the difference between the two.

R1, R2, R4, and R5 all need to be the same values, but it doesn't really matter what they are. There are a bunch of op amps that will work for this; I've got some TLC272 left over from a different project so I used that.

I've test benched this circuit on breadboard and it works OK. I need to get some parts and build it to test in the truck, but it should work.