I2C Sensor Isolator

Electrically isolate your sensors for better readings

What it is

Take measurements from several probes at the same time while connected to the same device. Probes often interfere with each other and cause shifted readings. The environment could also be causing readings to be off, likely due to a ground-loop or other electrical noise. Using this will eliminate those problems.

Using it

There are two sides, referred to as the INPUT and ISO. The input side is the four pins of your I2C bus; either 3.3 V or 5 V power, ground, SCL, and SDA. Connect them to your master controller. The ISO side is the output side and should be connected to whatever device you want to keep isolated and is supplied with 3.3 V.

The most basic configuration would be the sensor isolated from the master.

<I2C master> - <ISO> - <sensor>

You can connect more than one device to the ISO side. In this configuration the sensors will be isolated from the master, but not from each other.

<I2C master> - <ISO> - <sensor> - <sensor>

If isolation from the controller isn’t required, but isolation from two different probes is, you can connect the ISO board between the sensors only.

<I2C master> - <sensor> - <ISO> - <sensor>

And then there is everything is isolated from everything.

<I2C master> - <ISO> - <sensor> - <ISO> - <sensor>

But do I need one…

It’s hard to answer. The short answer is you probably do.

You will know you need isolation if you are getting bad readings when another probe is either introduced or taken out of your sample, or if you are getting skewed measurements intermittently (like when a pump is turned on or off, or maybe even when you touch the water), or otherwise unexplained measurement swings.


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I2C Sensor Isolator

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Support and Questions

If you have questions, find a bug, or have any suggestions you can send an email to [email protected].


Schematics are open and CERN OHL licensed.

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