I'm working on building an Ardunio Nano device that detects if automotive 12V circuits are on / off. I was able to successfully build & test a sample circuit provided Phil Frost.

The question I have is around saving space. I'm using this in a motorcycle so space is at a premium. The 4N25 uses 6-pins, even though I only use 4. I'm monitoring 6 separate 12V circuits and I'm wondering how to make it more compact.

Is there another chip (maybe a multi-optocoupler) or approach that will help me save PCB real estate?


1 Answer 1


Yes, there are quad optoisolators (one 16-pin package, either surface-mount (0.1" or 0.05" pitch) or old-fashioned DIP).

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Just go to your favorite parametric search engine, such as Digikey's and select 4 channel optoisolator.

Product Index>Isolators>Optoisolators - Transistor, Photovoltaic Output

Around 150 choices with different packages, CTRs, voltage ratings etc.


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