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ntyperteasy t1_ixf63yr wrote

This is a bit complicated for a DIY thread, but here, hold my beer...

I found one data sheet for that relay and it says it has a 1.6 V "voltage drop" which is an indication of the loss in the relay when on. This is a poor man's way of specifying the "on state resistance". This is why you are getting such a dim output. Since you are controlling the low level signal after the PWM controller, the voltage drop is too much. If you insist on doing it this way, then you need a way to increase the voltage again, but that seems a bit ridiculous...

If you buy the SSR from a place like Digikey that lets you sort by specifications and has detailed datasheets, you can sort them by the "on state resistance". They have models that range from 0.001 ohm to 10 ohms. I will guess you have one on the higher end of this range...

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irreligiosity OP t1_ixf8oxo wrote

FWIW, I also asked in the electrical engineering sub-reddit, but they have less traffic. I figured it is still technically a DIY question as I have no EE experience outside of DIY.

I was under the impression (maybe mistakenly) that I was able to get around the relay voltage drop by using the Mosfet. I had hooked up the gate pin to the output of the relay, the source pin to the PWM source and the drain pin to the LEDs. I guess I thought once the FET was open, the voltage would flow through it as if the relay wasn't even there.

I'm mostly just trying to solve this problem with things I have on hand because I've spent too much this year switching over to addressable pixel LEDs. I know I can technically buy a dmx receiver that outputs PWM for LEDs, but I'd unfortunately need several for different voltage strands.

Thanks for the help though.

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ntyperteasy t1_ixfcnbh wrote

Do you need to switch fast? Why not just a cheap mechanical relay? The voltage drop should be vanishingly small. Should be good for a year or two... And assuming your PWM is around 100 Hz, most AC rated relays should be ok with that. It's not RF....

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irreligiosity OP t1_ixfd9ok wrote

That didn't even occur to me, I have a bunch of SPDT relays. I just went and tested it and it works great. Thanks for the help.

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