Energy Monitor Optically Couples to Smart Meter

Hackers love to monitor things. Whether it’s the outside temperature or the energy used to take a shower, building a sensor and displaying a real-time graph of the data is hacker heaven. But the most interesting graphs comes from monitoring overall power use, and that’s where this optically coupled smart-meter monitor comes in.

[Michel]’s meter reader is pretty straightforward. His smart wattmeter is equipped with an IR LED that pips for every watt-hour consumed, so optical coupling was a natural approach. The pulse itself is only 10 ms wide, so he built a pulse stretcher to condition the pulse for a PIC microcontroller. The PIC also reads the outside temperature with a DS18B20 and feeds everything to the central power monitor, with an LCD display and a classic Simpson meter to display current power usage. The central monitor sends the power and temperature data to Thingspeak, along with data from [Michel]’s wood-stove monitor and a yet-to-be-implemented water heater monitor.

[Michel] is building out an impressive suite of energy and environmental monitors for his Quebec base of operations. We’re looking forward to seeing how he monitors that water heater, and to see what other ideas he comes up with.

27 thoughts on “Energy Monitor Optically Couples to Smart Meter

      1. My exact thought. It depend on how the microcontroller is programmed. I couldn’t find any program on the page but I may suspect that 10us can be tricky if you don’t use an interrupt.

  1. Nice design. I do get the impression that the kW hours differ on the analog vs. digital panel. Help us understand this? Is it average vs. Peak? instantaneous vs. peak? Is there a lag?

        1. Just read the hackaday.io page and see that your sensor is remote, so a long cable and 10uS could get eaten quicker than 10mS.

          Unfortunate that the meter on my swelling is not the type shown. Not sure if it has an IR LED on it.

          Thanks for the show. :)

    1. Qr is pretty robust. I often see desktop websites with qr codes to scan with the phone. Qr codes can be still read with one marker missing, scratches, and few cm scan distance.Some qr apps use back and white filter to boost recognition.

  2. Just wondering why the meter would have an IR LED that pulses every kW. I could understand it being a visible RED LED because you could see it pulse, but since we can’t see IR, I am baffled.

    1. A visible LED still isn’t human-readable – there’s no benefit. If it were up to me, I’d choose IR LEDs so the utility doesn’t get all sorts of frightened/angry kooks calling about being surveilled or seeing “trouble indicators”.

  3. A way to read all the registers via the IR port on the meter would be an awesome addition.

    For the record all the digital meters I’ve seen in AUS have red blinking LEDs. I’m not aware of any issues with that.

    1. Cue local evening news stations shaming the utility for seizing man’s equipment without authority, interfering with his patriotic hope of managing and conserving his own power to save $$, and to point out that newfangled “smart meters” are immune to the strong magnetic fields (we’re talking a big coil and lots of juice) which the old silver-disc meters were affected by.

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