every 15 seconds transmitting the data by RF seems to be expensive. The data can be stored in the unit and the network station can send a query every 24 hours and then the meter can reply. This will make the whole system more economical.
This is a very good technical article. It shows good engineering practices. It impresses me that it talks about the power consumption due to de-bounce switches software routine. Now I know that an alternative to that is to implement it with hardware. Anyone has a link to where I can find such kind of information?
Sorry, but this is Engineering 101. I was expecting a more original idea given our advances in power storage and "green" technologies.
How about a design for a meter that uses a micro-turbine which generates power locally based on the flow of gas/water through the meter and charges an Ultra-Cap?!? The loss in service pressure due to the energy extraction would be transparent to the end user (from what, 100psi?, down to maybe 90psi? the final regulator on my water heater regulates it down to 25psi anyway!). A teflon based magnetically coupled micro-turbine would be safe for use with natural gas since no spark hazard would exist, and there is a huge amount of potential energy available in a pressurized gas line! The size of the micro-turbine would be based on the max operating current requirements of the meter and scaled to support operation even during "low flow" periods. In this mode the battery would exist purely for backup power so a significantly smaller battery could be used (or possibly a rechargeable battery?). The power generating capability of the micro-turbine could also be sized in order to reduce the necessity for the extra design effort required just to pinch micro-amps from every area of circuit operation, as this article goes in great depth to describe. The question then becomes about guaranteeing the minimum life expectancy of a micro-turbine over that of a chemical battery, which since there would be no gears or mechanical parts to wear out should not be a problem.
@tcyr: I agree with you partially, harvesting power from the fluid flow would be nice to implement in a self-powered gas meter with battery backup (as is the case with many energy monitoring devices for electricity that scavenge the line power). The author does cover topics that aren't in a typical Enginering 101, perhaps 201 or higher!
@tcyr, there is few hundred patents about harvesting energy from flow of fluid, maybe we can not suggest this openly without violating other(s) patent rights, by product itself I have seen none, most likely the patent holders are not into manufacturing and manufacturer unable to pay patent holder cost. (I assume only, as this type of gridlock happened in other sector too). Again this article was about saving energy for design that uses battery and needed more TX power, I think the author address is clearly.
Change in design with circuits really helpful to increase the effeciency of different units. I have heard that we can save some money by installaing energy effeicent applinaces to our home. I was just thinking it was the myth. Two years ago i installated Rinnai tankless water warmer with new design and uopdated technology it make me amazed that almost about 20 to $40 has been saved every month due to it and its performance also better then the proviuos one.