Hello there everyone,
I am in the process of making a small variable voltage power supply using one of these common little LM2596 reference circuit boards, and a 16v DC power supply. It's a DC/DC step down circuit, that can take in anything up to 42v and output anywhere from 1 - 40v, with the upper limit being about a volt less than the input voltage. I've been using these boards for various purposes for a while, mostly bench supplies, but over time the cheap multiturn potentiometers on the board wear out.
I've had good results by replacing that pot with a larger single turn pot from sparkfun, but the tradeoff with that is that now the whole adjustment threshold for 0 - 40v is squashed into the 270 degrees of the single turn pot. It makes getting fine tuned voltages kind of difficult, and I thought I would be able to get around this by springing for one of these more expensive wirewound Bourns potentiometers. However, I'm getting some really weird behavior out of these pot's when I wire them to the board.
If I use my ohmmeter to check the pots beforand, I can verify that they range from 0 - 10K ohm over ten turns. The same ohmmeter shows the single turn pots go from 0 - 10K over one turn. However, when it's hooked up to the board, I can adjust it like normal about halfway through it's range (going from 0 - 10v), but once I get about halfway through it's range, it starts declining as I turn the dial forward.
If this description makes no sense I can try to make a video, but I'd really like to figure out why these potentiometers are doing this.
Thanks
Michael
