Notes from a small field

As revealed at the second homecamp, Current Cost have a very nice addition to their array of energy monitoring tricks: basically a little circuit board sporting a microchip (a PIC16F689 if my squiniting is accurate) and a wireless transmitter, so the gas monitoring item on my to do list is looking a little more interesting all of a sudden.

Richard has already hooked up his gas meter to Pachube but for a few reasons I have slightly different plans. Firstly, my gas meter is not the same. Possibly better and worse for this kind of exercise at the same time: it has an RJ11 socket for counting pulses… but it is covered and declares that only approved equipment should be used. Maybe not a huge deal, but it is gas and we did have three van loads of people looking for a gas leek in the meter cupboard recently, so kind of keen to avoid any… mistakes! Though I suspect that an optical solution, leaving the meter untampered, would not be any safer but would be easier to overlook next time the meter is read. Not that it has any reflective spot on the dials as far as I’ve seen so far. (Any recommendations from someone with experience counting pulses on a Schlumberger R5 meter, or similar, would be great.)

Second difference is that I’d like to go wireless, and if possible avoid needing an arduino. The gas meter is pretty much outside the other side of the house to my home server, with no power supply. So a wireless transmitter, like the one attached to the electricity cable, would be great. It just so happens I have one of those as well now- handy!

Thirdly, having a single display with all the meter readings on has to be the smart thing to do. The display I already have, and the one which will pick up signals from that transmitter, is the Current Cost. Perfect if I didn’t want a server running to connect up to Pachube/the internet, and also perfect if it’s already connected.

So all I need to do is:

• decide how to read pulses on the gas meter (peel off that cover, or come up with some Heath Robinson alternative)
• count the pulses and produce a pulse for the Current Cost transmitter development kit at the appropriate increments
• find out how to pair the transmitter as a gas channel, instead of an appliance channel (if that’s possible)
• use some gas

Update: after a bit more investigating I think I’ll be using the socket on the gas meter; I’m hopeful a repurposed spare cable from one of the many modems TalkTalk sent will do the trick. I was also wondering about simplifying the gas meter monitor to just register when I’m using gas, rather than worry about the rate. Some sort of 555 timer based circuit to keep the Current Cost dev board input 2 on between pulses maybe? The only thing that runs on gas is the boiler, so a simple on/off signal should be good enough to work out what I’m using. Dale’s recent roundup of HomeCamp 2 has some tantalizing hints of gas monitoring as well. (22 May 2009)