Re: [ATM] Electronics help needed - temperature control

[Kevin MIchael Zabbo <chaosopher23@yahoo.com>]

Silicon isn't as cheap for the amount of temperature
differences we're talking about here.  Silicon doesn't
vary as much as germanium.  The 1n34A diode (40 cents?
 Less?) is very cheap and predictable.  Besides, once
the temperature equalizes, you can flip a switch that
transfers the energy from the temperature sensor
system to a crystal radio, and tune in to a few AM
stations while you observe.  1n914's don't do that as
well. <weg>

Kevin

--- Don Clement <clement.focuser@verizon.net> wrote:

> 
> Kevin wrote:
> 
> > If you're as lazy as I am, you will want it
> automatic.
> >  A germanium diode or germanium transistor with
> the
> > properly-polarized amplifier after it will turn
> the
> > fan on for you.
> 
> No need to use germanium, silicon will do. The
> bandgap circuit is the basis
> for cheap linear temperature sensors such as the
> LM335
>
http://www.national.com/pf/LM/LM335.html#General%20Description
> . Every mixed
> signal integrated  circuit today; used in  ipods to
> cell phones, use the
> bandgap reference in some form. See:
>
http://users.ece.gatech.edu/~rincon/classes/ece4430/handouts/l39_bg.pdf
> 
> 
> 
> As with Gil, It's not laziness; just my parsimonious
> Scottish heritage.
> (Although not a pure single-malt, rather a Tennessee
> sour mash with bits of
> Old Hickory floating about)
> 
> 
> 
> Don Clement
> 
> Running Springs, California
> 
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> ATM mailing list http://www.atmlist.net/
> 


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