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Topic: My electrical power meter (Read 8 times) previous topic - next topic


Not a bad idea! Will look into it. Thanks for the idea.



Hi Ulf,

that's great project - the one what I searched for.
could you please give me some idea how to connect photoresistor to arduino? some sketch should be great.
I want to read power usage from 3 electric meters - one heating system, one water heating system and air exchanger system.
thanks in advance



Sure, here comes a schematic:

The light resistor is connected to 5v and pin 3 and. And there is a 4 Mohm something resistor connected to pin 3 and ground. So if the light resistor sees darkness pin 3 is connected to ground and if it sees light pin 3 is connected to 5v. That vay i can read changes from LOW to HIGH on pin 3.



Nice project :)

I've always wanted to know exactly how much energy I'm using, and now I'm just days away to get my own solution working :)

I do not have any experience in Arduinos, but I plan to use an ATmega(8,16,32), I'm not sure what will suit my application best. Those computers do have UART interface and that is good news since the old laptop I uses as home webserver has a RS232 (serial) interface. The plan is to buffer the meter reading in the ATmega and send to laptop (server) and perhaps use another ATmega coupled with a DS1620 digitalthermometer. And then correlate used energy with outdoor temperature :)
Python and pySerial is quite easy to use when interfacing with UART.

I tried various solutions before ordering some ATmega.
The first try were 6-7 years when I studied, my apartment had the meter in my office/study, and I used my (only) optical mouse and taped it to the meter with the optical sensor right above the light, and were able to make a Java program that registered changing states in the serial transfer. It was a bad solution since I were a student and a new mouse would cost too much.
Just recently I tried to use a photoresistor and photodiode with a parallel port to do the same trick, but i was not able to get any stable signal through.

Mmmh, should perhaps have something measuring the take wind speed also...

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