Quote:
Originally Posted by rjb
I am currently working with Paul at Marshall to figure out the best way to build and market these dimmer switches as they will need PCB boards manufactured, and I will need to be able to do a minimum quantity to recoup the setup costs. I will keep everyone posted.
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I've been doing a little research on my end with one of the gauges. The first thing I learned was that you
must connect the +12V line. Just wiring to the orange wire and ground will
not turn on the light in the instrument.
Having determined that, I wired the red wire to +12V and a variable voltage power supply to the orange wire. One would assume that cranking up the voltage slowly on the orange wire should gradually light up the gauge, right? Wrong! The light goes from off to
full on at about 7.5 Volts and doesn't get any brighter as you crank the voltage higher.
Just for fun, I switched the red and orange wires so that the variable was on the red wire and the +12V on the orange wire. Then, as I cranked up the voltage on the red wire I could see the light flicker to life at about 7 Volts. As I cranked the voltage higher it gradually got brighter all the way to full on at 12 Volts. Not what I expected, but maybe good enough to work with the signal off the dimmer. I haven't gotten into that yet, so I don't yet know what the dimmer feeds to the OEM dash lights.
For you electronics geeks (like me), I suspect that some sort of interface circuit may be required to get the gauge lights to track with the dash lights. There are multiple ways to approach this problem, but maybe something as simple as an op-amp with gain and offset (to be determined) would do the trick. A brute force approach would be to digitize the output of the dimmer switch and use that to drive the address bus of a PROM lookup table driving a DAC followed by an op-amp to supply voltage for the gauge lights.
That all sounds like a lot of trouble to simply get the gauge lights to track with the dash lights, so maybe it's just for the purist. The practical approach is to just wire the red and orange wires as directed in the instructions, adjust the dash lights until they match the gauges, and leave it at that.
Tom S