10 points for Tracy....
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Posts: 46,084
Thanks Tracy - if we were on a point system here, you would likely have a
barrel full!
Yesterday I was working with a standard, commercially packaged process
controller with a 0-10V output, and I had an impedance mismatch with my A/D.
I had tried raising the divider resistance and adding a .1 cap at the A/D
w/o results. I was about to give up on that approach, and was about to work
on a buffer amp when you responded with verification that the .1 cap should
have worked. You even added a wonderful explanation of why it should work.
Today, I have connected another controller, and found that the .1 cap and
the higher resistance works well. Oh, yes, I checked the output first - the
original controller definitely had a defective output section - perhaps the
low impedance was the culprit. In any case, I'm back to the 20+ year old
texts to jog the memory so I can calculate the impedance now.I want to be
sure that I don't end up with another dead controller.
Bottom line was that your recommendation was right, and I just wanted to say
thanks, again.
Chris
barrel full!
Yesterday I was working with a standard, commercially packaged process
controller with a 0-10V output, and I had an impedance mismatch with my A/D.
I had tried raising the divider resistance and adding a .1 cap at the A/D
w/o results. I was about to give up on that approach, and was about to work
on a buffer amp when you responded with verification that the .1 cap should
have worked. You even added a wonderful explanation of why it should work.
Today, I have connected another controller, and found that the .1 cap and
the higher resistance works well. Oh, yes, I checked the output first - the
original controller definitely had a defective output section - perhaps the
low impedance was the culprit. In any case, I'm back to the 20+ year old
texts to jog the memory so I can calculate the impedance now.I want to be
sure that I don't end up with another dead controller.
Bottom line was that your recommendation was right, and I just wanted to say
thanks, again.
Chris