They all need to be calibrated independently because all junctions (diode
drops) are not exactly the same voltage. If you want more "gain", put two or
more in series. I use a simple circuit in my bus as a thermostat for air
temperature. Two diodes in series feeding an op amp comparator/schmidt trigger
to drive a relay via a transistor.
Rick

Tal Bejerano - AMC wrote:

> 10x a lot!
> so as I understand I can measure the voltage drop in any temp ? should all
> diodes react the same or should I calibrate each circuit?
>
> Regards
>
> Tal Bejerano
> AMC - ISRAEL
>
> -----Original Message-----
> From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On
> Behalf Of Jinx
> Sent: Wednesday, May 22, 2002 12:13 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: 1N4148 as temp probe?
>
> > Companies like Maxim make chips that will use a transistor
> > as a temperature sensor for use inside PC's, as the Pentium
> > chips have a transistor temperature sensor built in to allow
> > control of fans
>
> Like this
>
> http://www.national.com/ads-cgi/viewer.pl/ds/LM/LM84.pdf
>
> from
>
> http://www.national.com/appinfo/tempsensors/
>
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