Hi I have bought the SCT013-30 1V in error with the internal burden resistor.
Sorry if this has been covered before, I have searched around a bit.
Given this sensor outputs -1v to +1v this is not suitable for my arduinos ADC.
I can either use a 3.3v or a 5v arduino/atmega. I plan to integrate it into my current mysensors/domoticz setup to measure hot water use/cost. I have never worked with -ve voltages before so am a bit confused sorry.
I think I should be able to halve this signal to -0.5v/+0.5v with a simple voltage divider. Then I would like to boost the whole thing by 0.5v to give me a sinusoidal signal ranging from 0v to 1v which would be perfect to measure against the atmegas internal 1.1v reference.
Not sure what this circuit would look like though…
Any help greatly appreciated.
Thanks,
Matt
Your easiest solution is to use the circuit in “Learn - CT Sensors - Interfacing with an Arduino” and simply leave out the resistor marked “Burden 33 Ω” because you already have a burden inside the c.t. housing.
Read through that page, it explains how we handle the problem. That also explains a little about how we measure alternating voltages, it sounds as if you’re a bit confused by that. If you need more help, ask.
EmonLib uses the supply voltage as the reference, but the supply voltage is calibrated against the 1.1 V reference, which although stable, has a large uncertainty in the value. But calibration can take care of that, and how to do it is also in the “Learn” section.
Then at the bottom of the page is a link to a “current only” sketch. You’ll also need to download and install emonLib from GitHub to get everything working, here are the instructions for installing all the libraries (Win10). (If you want a Mac or Ubuntu version, ask.)
Thankyou very much for your reply Robert.
I think I understand now. The divider in the circuit (did read this earlier but misunderstood) is not for the input, rather to halve the 5v or 3.3v from the arduino in order to condition the sensor signal to swing around the divided voltage keeping it all positive and within either 5v or 3.3v limit. Am off to work shortly will have a fiddle round sometime this coming week and get back to you if I have any further questions.
Again thankyou…
Matt