Problem with low voltage reading on encoders


I am using the Optical Encoder Pair Kit for Micro Metal Gearmotors, 5V

Below is a shot of my oscilloscope for the encoder voltages. For some reason the output voltages are very low about 1.5V for ChA and 0.5V for ChB.

I have checked Vcc is 5V. I have also tried moving the encoder wheel back and forth on shaft. I see the waveform change shape however voltage doesn’t change.

I am not sure what else could be causing this. Does any one have any suggestions?


Hello, Peter.

I am sorry you are having trouble with the optical encoder kit. The larger amplitude waveform in your picture looks like what we expect to see as an output of that board. On the product page for the 5V encoder board, we have a picture of an oscilloscope capture at 30k RPM that shows a waveform with approximately 3V peak-to-peak, which is similar to what you are seeing:

As for your small amplitude waveform, you might check the alignment of your sensor board with the back of the micro metal gearmotor. A large difference in magnitude between each waveform could indicate misalignment or a non-flush contact with the back of the gearmotor.