Evaluated the Advanced Photonix Ceramic Photocell NSL-5162 as the LDR part of a Vactrol audio attenuator. It works well with an ordinary low-intensity red LED and is not too sensitive to ambient because my gadget has the LED bent over and atop the LDR. Another PCB has the test circuit with a driver transistor.
I drove the test procedure from the analogue pin of an Adafruit M0 dataLogger which has a true ADC. Most MCUs have fake ADC from PWM. Not good enough. Pin A1 provided analogueRead so that results could be recorded and graphed.
So the input to the test jig is linear but the LDR voltage on A1 is a curve. This does not matter for on-off operation such as muting. Otherwise, the control voltage needs to be corrected so that the LDR behaves like an audio pot.
I drove the test procedure from the analogue pin of an Adafruit M0 dataLogger which has a true ADC. Most MCUs have fake ADC from PWM. Not good enough. Pin A1 provided analogueRead so that results could be recorded and graphed.
So the input to the test jig is linear but the LDR voltage on A1 is a curve. This does not matter for on-off operation such as muting. Otherwise, the control voltage needs to be corrected so that the LDR behaves like an audio pot.
