EmonTx Shield for power monitoring in Arduino serial monitor

Hello, I am new to this community and I am not very familiar with how everything works.

I am working on a power monitoring project where I want to monitor the power consumption of an electrical cooking device. What I have in mind is using a CT sensor (around the electrical cord of the cooking device) connected to an emonTx shield to read the power consumption of the device using an Arduino. The Arduino would be connected directly to a computer via USB and I would read the data inside the Arduino IDE serial monitor. I don’t need any RF transmitter since my computer will be next to the cooking device.

Is it possible to do this? Has anyone done a similar project before?

Thank you in advance,


I think many people will have done a similar thing.

But there might might be a problem, so I need a few answers.

What exactly is your “cooking device”?

What type of heating does it employ (e.g. quartz halogen, induction)? and how is the quantity of heat being delivered controlled within it - are the heating elements switched on and off rapidly, for example?

What exactly is the electricity supply? You have not given the country where you are, but I see from your IP address that you might be in Canada? Believe it or not, this is why we ask for your country, because there are quite different systems in different countries, and that can have an important influence on what you need.

Hi Robert, thanks for answering so quickly !

It’s a gourmia GKM9000 multi cooker. It can weight, chop/stir and heat at the same time. You send a command to the device with the target temperature. Once it reaches it, the device will start throttling around this temperature. When that happens, the heating element is switched on/off quite rapidly (approx. every 10 seconds). I am not sure about the type of heating but it is not induction.

Indeed I am from Canada. The device is plugged in a regular 110V US/Canadian electrical outlet.



A good job I asked - that’s totally irregular compared to the standard UK system that we’re used to and the whole Emon system was generally designed for.

I suspected something like that might be the case then I wrote “there might be a problem”. That means you need to use the CM (continuous monitoring) library emonLibCM, and not plain emonLib. I don’t think there’s a “standard” sketch using that, so you’ll have to use one of the examples that come with emonLibCM in the download zip file:

and customise it to use the I/O that you have (Voltage is AIO 0, current inputs 1 - 4 are AIO 1 - 4) and of course you must write the parts to send the outputs that you need.
You can of course (and probably should) leave out everything related to the RFM12B/RFM69CW radios.

As you’re using just one leg of your supply, you want (for accuracy) a 120 V a.c. adapter giving approx 9 V output nominal - expect around 12 V open-circuit) to measure the line voltage, and a single c.t. on the “hot” leg supplying the cooker. You can increase the c.t’s sensitivity by having a multi-turn primary winding (5 turns will make a 100 A c.t. into a 20 A one, for example). That’s better than increasing the value of the burden resistor, which increases the errors as well as the sensitivity. The a.c. adapter is in addition to the Arduino power supply - for which I’m told you should use the 7-12 V input and the on-board regulator in preference to the 5 V input.

If you need more help with calibration, ask again.