Problems with S18V20ALV

I have two of these variable regulators, but I can not use the potentiometer to set a stable voltage. I turn the pot slightly and it jumps to 12.5V then I can adjust it but after removing my screw driver the voltage just drifts down. Is there a schematic I can access so I can just remove the potentiometer and install a fixed resistor?



I am sorry you are having trouble setting the output voltage of your regulators. We do not release the schematics for the S18V20ALV regulator, but it would seem very odd to me for the potentiometers on them to fail in the way you described. Please note, that regulator has a maximum rated output voltage of 12V (though it is possible that your particular units can be set up to 12.5V). Since very small adjustments of the potentiometer on the upper end of the voltage range can cause large changes in the output voltage, I suspect that you might be turning the potentiometer too far and thus setting it to the lowest output voltage, and it is just taking a few moments for the voltage to fall. Does the drift still happen if you set the output to something lower like 9V?


Can you tell me the value of the potentiometer at least?

It is a 100k potentiometer.

Another thing that might be related to your issue that I forgot to mention in my last post is that we recommend using a light load like a 10k to 100k resistor while setting the output of this regulator. Are you using a load when trying to set the output voltage? If so, what kind of load is it?