I would like to use an analog meter movement to display a "window" reading. For example if I want to monitor the output of a 120V isolation transformer whose voltage I would like to have within +/- 5% of 120V , a meter reading 0-130V would not provide the level of resolution that I really care about. I would like to have the meter read within a window of 110V to 130V, with the desired 120V right in the middle, so that you can tell from a quick glance if the needle isn't pointing straight up, there is a problem. And further, you will be able to tell quickly if it's off by 2V or 10V, without having to stare at the meter through a magnifying glass and calculate minor divisions on the scale.
I'm guessing a bit of circuitry will be required in excess of the typical trim pot and series resistor. Maybe some Zener diodes, maybe an op-amp or two. What will it take? Does anyone have a canned circuit for this? As usual, I've already googled before asking, and I'm googling while I wait for answers, but as of yet I haven't found anything.
I'm guessing a bit of circuitry will be required in excess of the typical trim pot and series resistor. Maybe some Zener diodes, maybe an op-amp or two. What will it take? Does anyone have a canned circuit for this? As usual, I've already googled before asking, and I'm googling while I wait for answers, but as of yet I haven't found anything.