[EE]Flow Sensor possibilities by cdb .

Some years ago I designed a water usage meter project for N&V magazine that used a ready made turbine flow sensor. The drawback with this component was that it was expensive from the DIY makers point of view, exacerbated by the fact it was only available from RS Components. I'm thinking of revamping the sensor to make it easier to 'roll your own' and to this end I've got four ideas, which I'd like thoughts on. Option 1. Heated coil around water pipe / downstream thermister detection technique - measure temperature at coil and at thermister - work out rate of cooling = flow speed in Ltrs/minute. Option 2. Use either a differential or maybe two pressure sensors inserted into pipe, difference in air pressure = rate of flow - not too sure on this. Option 3. Use a Piezo Film sensor like the Parallax tab device - to measure pressure or vibration or maybe cable like the road speed sensor units use. Perhaps this might work wrapped around a pipe or easilt inserted into a section of pipe Option 4. Similar to #3 use the flexiforce or muscle wire sensors. What I'm looking for is something that would be easy for a magazine reader to construct, is relatively easy to make reasonably accurate and best of all slightly novel, hence options 3 and 4. Naturally it would be Pic'arised at some point or maybe Zilogged Thanks for your thoughts. Colin -- spamcolinKILLspamTakeThisOuTbtech-online.co.uk -- No virus found in this outgoing message. Checked by AVG. Version: 7.5.427 / Virus Database: 268.13.18/506 - Release Date: 10/30/2006 6:15 PM