Not sure about this electronic component


Joined Mar 30, 2015
Welcome to AAC!

It appears to be some custom device. The only way to tell for certain what it is would be to remove the coating from one. That doesn't have to be a destructive process, but it could be.

Other options are to measure for resistance and capacitance or use a signal sweeper to see what it's response is with respect to frequency.


Joined Jan 8, 2017
You could trace out the schematic of the board around one of these devices as this would give an idea about what function they do. As there are a number of opto couplers close to these items it is probably related to optical isolation of a number of inputs or outputs. You have a distinct advantage over the rest of us in that you probably have some idea of the function of the board and what is connected to the connector close to these components.



Joined Apr 27, 2007
Using the signal sweeper method, I found out it's a high pass filter.

Thanks all for the response!
Looked passive in nature, indeed. By the way, was the response similar to an RC filter, or more like an LCR filter? There are three passives. One of them might be an inductor, due to its odd shape. Or it can be just the epoxy that is misleading.

Kind regards, Samuel Lourenço