Part 2a: The Sensor Bar (Arduino Gas Meter project)


Ok, so here we are a few days later than expected. I’ve been a bit too busy to tinker lately, but I’ve made some interesting progress. I’ll keep this post brief…

Firstly, the phototransistor I ordered from Maplin turned out to be of limited use since it’s ‘detection range’ is a little bit too small to work with the gas meter properly. Also, due to the siting of the gas meter within my property (in a cupboard, with a chair in front of it!), I needed the sensor to be remote to the Arduino. So I ordered a Fairchild Photoreflector from Active Robots. On the surface, it’s everything I need (a photoreflector with wires already attached). Very inexpensive.

Fairchild Photoreflector

Simply dropped this right in place of the existing photoreflector and it works a treat.

Experiments with mounting the sensor to the gas meter

So far, having attempted to mount the sensor on a little bracket in front of the meter, I can’t get an accurate reflection (annoyingly there is a clear plastic cover over the reflective disc which is at a 45 degree angle – sort of – and curved). Having run out of Blu-tac on a previous tinkering experiment, I’ll have to go get some more tomorrow in order to experiment with that.

Reading the meter

I just got my hands on a Nuelectronics LCD Shield so I’ll be setting that up soon to display the meter value.

More to follow soon…


5 thoughts on “Part 2a: The Sensor Bar (Arduino Gas Meter project)

  1. Ken


    Thanks for the fresh inspiration. I built something similar for pulse counting the gas meter when the gas utility changed my gasmeter to the odometer type in Nov. 2004.

    It worked quite well and I used a small PIC to count the pulses. Unfortunately the photoreflective sensor was not really a permanent fixture and got lost the following summer when we had to shunt stuff around whilst building a house extension.

    I’ve now recreated the photoreflective sensor on a small bit of veroboard, which clips to the correct position on the meter with a couple of drilled holes in the veroboard, which are a press-fit over small plastic pegs provided on the meter. There is a cut-away in the plastic underneath the dial where the manufacturer clearly intended to mount their own opto detector unit.

    I use an additional transistor to make the sensor more sensitive and I can actually see the various digits go past with a distinctive change in the analogue voltage which it outputs. When the reflective zero goes past the output produces a very distinctive full amplitude pulse.

    I now need to couple this into my Arduino and ethernet shield and hope to get the pulse count up to Pachube in a similar way to yourself.

  2. Hi,

    Nice project – I am looking at doing the same to monitor gas usage – did you get any further than step 2a ?


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