# Convert 1v/ -1v AC to 0v-1v AC (SCT013)

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 thoughâ€¦
Any help greatly appreciated.
Thanks,
Matt

Your easiest solution is to use the circuit in â€śLearn - CT Sensors - Interfacing with an Arduinoâ€ť and simply leave out the resistor marked â€śBurden 33 Î©â€ť 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 youâ€™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 â€śLearnâ€ť section.

Then at the bottom of the page is a link to a â€ścurrent onlyâ€ť sketch. Youâ€™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.)