Has anyone added a pmw to dim dash lights from stock switch

[chewychevy67]

I have been looking and I'd love to add led lights to my dash lights but I find them really intense at full output and would love to be able to dim them from the factory switch somehow. Is there a modifications out there that will make this possible? Anyone done this out there?

[chewychevy67]

Or any mods that I can add that will let me dim my led dash bulbs that works well?

[dmjlambert]

I have thought about it. It may be possible to wire the stock rheostat as input to an Arduino or other small microcontroller, and have the microcontroller read the rheostat position and produce a PWM output and amplify the PWM signal with a transistor to dim the LED bulbs. But it is a lot of trouble just to have LED bulbs fully functional in a position where incandescent bulbs just work. I have not yet thought of an advantage LED bulbs give anywhere on the truck except brake lights.

I put some LED bulbs in the dash and found they look OK and they do dim from the stock rheostat a little bit. I took them out and put the incandescent bulbs back in. If increasing maximum brightness is the point, then I think 168 bulbs to replace the 194 bulbs would take care of that. But so far I just have the 194 bulbs in there.

[dmjlambert]

Here is another idea that may be cheap to try. It may be possible to get something like this:



And remove the variable resistor from it and wire in its place the stock rheostat. It would involve removing the headlight switch and looking at it and figuring out how to separate the connections of the rheostat from the regular truck wiring, and add wires that go to the PWM controller instead. I believe the stock rheostat only has 2 wire connections if I recall, and it would need to be modified to have 3 connections, perhaps by soldering a wire on the end of the coil.

[body bolt]

What you need is a voltage-controlled PWM. Here's one simple circuit that could be adapted for this purpose. Use a single-supply LM324 opamp instead of 741s. The LM324 is a quad device which would also cover the two 741s in the sawtooth generator. The PWM output would need to be buffered as the 324 has a current limitation of 40ma but an additional 2N2222 could be used for that.

[Rich72C10]

Originally Posted by body bolt

What you need is a voltage-controlled PWM. Here's one simple circuit that could be adapted for this purpose. Use a single-supply LM324 opamp instead of 741s. The LM324 is a quad device which would also cover the two 741s in the sawtooth generator. The PWM output would need to be buffered as the 324 has a current limitation of 40ma but an additional 2N2222 could be used for that.

Make a few of those up for us LOL!

Times like this I really miss my dad - he was a electronic's component guru. He could design cool things going back to vacuum tubes forward (or at least before things went surfaced mounted) on a napkin. Heck, he even made his own low-power FM Stereo radio transmitter in his garage to play his music to his radio headphones while doing yard work. Damn thing could be picked up ~10 miles from his house!

[body bolt]

Originally Posted by Rich72C10

Heck, he even made his own low-power FM Stereo radio transmitter in his garage to play his music to his radio headphones while doing yard work. Damn thing could be picked up ~10 miles from his house!

Before BT.

Your dad sounds cool. I've worked in SW/HW for 47 years and still enjoy it as much as I always have. The things we have now were unimaginable back then.

[Rich72C10]

Originally Posted by body bolt

Before BT.

Bingo!

[dmjlambert]

That voltage-controlled PWM sounds interesting.

[chewychevy67]

I tried something simple here and I think I can adapt this into my switch and will work nicely for my needs . Just a pointometer from a 60s cadillac twilight sentinel used in the powerHere's a video
https://youtu.be/ojk2TTmkFiM

[chewychevy67]

Can you view it now? I'm not good with computers lol.

[dmjlambert]

Yes thanks. I will give it a view.

[dmjlambert]

I think the stock rheostat in the headlight switch will do that as well. If using LED bulbs it won't smoothly dim all the way down to off.

[chewychevy67]

Mine doesn't dim nothing at all. It all in or nothing. But I did notice that the pointometer doesn't quite get the bulb to full 100% brightness and it will not work with a incandescent bulb.

[dmjlambert]

Then I suppose the potentiometer will have to do, or figure out how to do PWM.

[chewychevy67]

I can confirm that the light only goes to 8 volts with this pointometer and the lights are not bright enough to read in the dark.