External Moderators tmoulder Posted April 25, 2011 External Moderators Report Share Posted April 25, 2011 No, I'm not doing yard work I'm using a potentiometer to pipe 0-10 VDC to an analog input on an E1B snap IO board. The problem is resolution - the active portion of the pot is very small, and since the resolution on the analog input is also tiny, the active area encompasses all of 24 measurement units out of 1024 for full swing. To overcome this, I applied full 24 VDC to the pot, and set up the mechanism so the active portion ranges from 9-10 VDC. This brought my resolution to 92 units, sufficient to my purposes. The problem - at 15VDC or more, my input will go *poof*. Not a big deal right now, but in the future, if somebody changes the pot or spins it somehow without consulting me first, they may well let the smoke out. So I've been exploring ways to limit the potentiometer output by restricting it to 12 VDC or less. A zener does not seem suitable because I need the full voltage range below 10 VDC. I don't want to divide the voltage and lose resolution again. A diode clamping circuit I built was unsuccessful in tests. And lastly, all the documentation I can find on the web is all about clipping and clamping AC signals, not DC outputs. This seems like it would be a common problem in these analog circuits, and I was hoping somebody might have an idea about a solution. Thanks! TM Quote Link to comment Share on other sites More sharing options...
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