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I have an Arduino project where I intend to use 6 non intrusive current sensor model SCT013 (100A/50mA) manufactured by yhdc.com

As reference voltage on examples I find at the internet it is suggested the use of 2 10K resistor connected in series from 5V to ground, the reference voltage is extracted from the middle connection between the resistors (2.5v).

Question:

In the case of six sensors will I have to use 6 independent voltage dividers or can I use a single divider as reference for all sensors?

I am concerned the interference between sensors may cause reading imprecision.

Thanks in advance Paulo

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I assume you refer to a circuit like this:

schematic

simulate this circuit – Schematic created using CircuitLab

The "reference" you speak of is not a reference - it is a virtual ground. A ground reference that is at a different potential to the Arduino - in this case 2.5V higher.

Since it is just the ground for the circuit you can use the same one for all the current transformers without problems.

If the offset voltage were applied to the output (as is often done for active devices that create an AC waveform, such as audio signals) then you would require a separate offset voltage for each one, since otherwise you would be connecting all the outputs together, which would be bad.

You can also "reverse" your thinking. The "offset" voltage you apply is ground, and the Arduino's "ground" is 2.5V below that. It's all relative.

  • Ok, understood. How about the capacitor C1, should I use a higher value, or, does it matter if I use like 100 microF instead of 1? Thanks Paulo – Paulo Borges Nov 10 '17 at 5:11
  • Not really, no. It's to reduce the impedance of the voltage divider. – Majenko Nov 10 '17 at 10:22

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