Rain Detector
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From: Tom Lucas on 5 Jun 2006 05:42 "Steve" <steve(a)deletethissjwilliams.com> wrote in message news:690j72p9fgktp1cjv95eur1c60gpriai8i(a)4ax.com... > On Fri, 26 May 2006 14:43:47 +0100, "Tom Lucas" > <news(a)REMOVEautoTOflameREPLY.clara.co.uk> wrote: > >>As for the detection, the water level detection in the Industrial Boiler >>Control I'm working on uses capacitance probes and is pretty sensitive. >>They >>work by using an oscillator whose frequency varies with the capacitance of >>a >>probe dipped in the water. Measure the frequency - know the depth. > > Picking up on this point - I'm interested in making an accurate > aquarium level detector at the moment (saltwater) , and wonder how > good this method could be. In an ideal world something like 1 mm > resolution would be good. Could this method achieve this. Any > suggestions on the general type of oscillator and ballpark frequency > that might work best? > Sorry I haven't responded for a while - I was off last week. I'm pretty sure you can make it work to just about any reolution if you have an accurate enough design. I don't think our probes have 1mm resolution but they are 4 feet long and don't need that kind of accuracy. I didn't design them though and so I have no idea what type of oscillator or frequencies to start with. Knowing our lot numbers like that would be bitterly guarded secrets anyway :-( In a good controlled environment like an aqaurium then you might be better using load cells to weigh the tank. I was speaking to chap in the pub yesterday who works with weighing machines who reckons he uses a load cell with a few thou of movement which will measure up to 20 tonnes with a 200gram resolution! I was impressed. |