Try using a dew sensor from a VCR. these devices are used to detect
condensation in a VCR to avoid damage. They are a small device and I dont
think they should cost to much.

Mathew Cohen
----- Original Message -----
From: Jinx <joecolquitt@CLEAR.NET.NZ>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, October 26, 1999 10:15 AM
Subject: Re: [OT] Humidity sensors


> Any chance a thin slice of conductive foam could be used somehow ?
>
> Joe
>
> > Hi, all - need a cheap, cheap, cheap "fog detector" sensor, to tell when
> > a piece of glass is getting fogged up.  I've thought of using a
> > LED/photodiode pair, which has possibly problems;  Could use an
> > enclosed/open thermistor pair, I suppose.  Anyone have ideas?
> >
> > What I need is a signal "Glass is fogged, or getting slightly fogged" /
> > "Glass isn't fogged", it'd be nice if this is $1 or so in price, I want
> > to turn a fan on & prevent fogging of the glass, if I can.
>