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August 2, 2011
about 3 years ago
Forgot to mention. my system that this is connected to uses 28V.
I purchased 30 of this for a project. My thought so far are as follows.
With a line unloaded there is a lot of noise in the system. You will have to sample the sensor at high rate and then average out so many samples to get something reasonable. I have an idle system at 20mA and it’s very difficult to detect, however when running it at 300mA then once can see the change in output voltage from the current sensor.
Arduino Uno Analog In from Vout on Current Break out board.
To calibrate, I used a multimetere and connected it in series with this sensors with the load turned off. Using the map() function in Arduino IDE, I remapped the analog 10-bit back into voltages, then maxed out the Vref. Read it’s value in arduino (mine was 4.93V) the lowered Vref and keep gain as high as possible. Once your arduino reads Vout as something lower than 4.93V, you can lower Vred (Slowly) till you have a voltage you want to work with (I used ~2V) then apply a current. (20mA) and check out how much Vout changed in arduino. (Mine changed from 2.0 to 1.98V) I did noticed that with this method you will get an inverting effect. Meaning more current actually lowers the voltage. This can easily be fixed with map() again.
So far I wasn’t able to really measure 20mA decent since all the noise causes lots of errors in reading. Sampling at 1kH and then averging every ¼ of a second should give decent results.
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