To pick your knowledge, how can I test the log plot on a potentiometer?
I imagine a chart defining dbv in vs dbv out, with the ability to rotate the shaft to full range and then plot.
This would be very easy to make in an application. Never thought of this kind of graph. I’ll put it on my to do list.
1 Like
You would need a stepper motor coupled to the pot which stepped “x” degrees, measured a DCR value and stepped again. Then plot the results R vs angle. Pots can be 270/300 (or more) degrees full rotation.
1 Like
My most common pots are ALPS RK-27 series
I thought about this measurement, but a dBV to dBV measurement as proposed does not make sense because the input and output of a potentiometeris always lineair. If the input voltage doubles then the output voltage also doubles for a certain angle.
Only a dBV to angle measurement makes sense.
So a stepper is indeed needed. Or some sort of scale and and a list of manual operations where the software tells you to change it to some angle and than press a button to do a measurement.
Yes, the stepper motor drive is necessary to get the in and out values.
This is the Goldpoint plot, it is a stepped attenuator. So, for the ALPS it would take a stepped motor to drive to the 24 points.
James,
The 24-position Goldpoint taper (blue line) was a one-size-fits-all approach
I adopted in 1995. It is the taper used in both resistor lists I sent you -
and should be right for most systems, optimized to give more usable steps for a
24-position rotary switch stepped attenuator.
