What photo resistor to use for the power meter?


i would like to built the power meter, described here: https://esphome.io/cookbook/power_meter.html

I use this ESP32 device: https://www.amazon.de/gp/product/B071P98VTG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I already have flashed it and this is working, even it appears in my WLAN.

But i have problems which photo resistor to use?
May someone please give me a hint which one and how to connect which cable to which GPIO PIN? Surely one of is the mentioned GPIO PIN12 as mentiones in the code.

Thanks in advance

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I have done a bit of research on this. However i did not follow through to the end because I went a different route (my meter sends radio signals I went with This )

If your meter has a visible to the naked eye blinking light then any Photoresistor well work.

Some basic hookup info Here and I think you would use a Binary Sensor component to read the blinks.

Something like that.
Sorry for the brief description, like I mentioned I did not follow through with this solution.
I hope it’s of help.

Edit: I found a link I had bookmarked for reference, that is related. It might be of help to you. https://forum.arduino.cc/index.php?topic=416054.0

Thanks for the comment. My Power meter is unsmart today.
Just ordered some photo resistors and will try. Think ist should work within the dark case.
Had similar setup on my old long ago Domiticz setup with Mysensors.
Esp32 untilgbar nie is much more comfortable with WLAN.

Will report once up and running smoothly.

/ Ralf


need your help again.
As posted above, i have purchaesed this ESP32. Flashing has worked very well and i see it in my hass.io (latest version).

I also purchaes these photo transistors.
Added one of the pins to GPIO12, the other one to 3.3V ping of the ESP32.

Built is like described on the ESPHome page (link).

But i still got no data from this. So i am unsure what is wrong with my setup.

/ Ralf

EDIT: just saw this post: Issue with pulse counter component!

Will try to add the resistor and give feedback if this works for me.

You can check my project HERE - there are links to purchased components
I used ESP8266 and at that time EasyESP but I already converted it to ESPHome.
At the moment, on the same ESP8266 I have:

  • Pulse sensor for energy measurement
  • Barking sensor :wink: for my dogs
  • PIR sensor
  • Illumination sensor
  • DeAUTH WiFi attack sensor :nerd_face:


I like to do the pulse counter for power meter but there is no ready power source at the meter! Battery won’t work as deep sleep won’t be effective since the ESP8266 need to count the LED pulse and send out data with Wifi but I’m not sure.

There is unused TV inlet (RG-6 coaxial cable) nearby to the meter that is wired to the rest of the apartment, can I send 12V or 5V DC current with the coaxial cable from within the apartment to the ESP by soldering the 2 conductors of the coaxial cable for less than 10 meters? Of course will need to drop to 3.3V at the ESP.

I don’t have the knowledge to help you here.
Maybe someone else will pick this case up?
Or just #yolo and test :nerd_face:

my power meter sits inside my safety cabinet. So i used a step-down converter to get 5V. Costs me (here in germany) about 15 EUR.
I suggest to use only safe things otherwise you’ll have potential electrical saftey issues when making your home smart.

/ Ralf