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NNTP-Posting-Date: Fri, 13 Dec 2002 18:01:12 -0600
From: email@example.com (John Fields)
Subject: Re: thermostat for heat lamp w/ remote probe
Date: Sat, 14 Dec 2002 00:06:18 GMT
Organization: Austin Instruments, Inc.
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On Tue, 10 Dec 2002 23:34:04 -0600, "Jason A. Arends"
>i currently use a heat lamp hooked up through a rheostat that i can
>manually adjust for temperature based on a digital thermometer with an
>in/outdoors feature (outdoors uses a probe on a wire). i'd like to make
>a thermostat that will control the intensity of the light based on the
>temperature according to a setting that i make on a dial. i don't want
>it to be an on/off thermostat, but a continuously variable design so the
>temperature is more stable. a common one used is here:
>http://helixcontrols.com/prod_dbs1000.htm but it's digital and costs
>$120. i don't need any fancy features, just a dial. it doesn't even
>have to be calibrated, i can find the correct temp by trial and error.
>the temperature sensor should be small and on a long wire, like a
>thermistor probably. the probe goes in my gecko's cage. is this
>something that can be done easily? i've seen designs for a temperature
>controller using a wheatstone bridge but i have no idea how to make the
>AC vary with this idea.
If you can get ahold of a copy of the sixth edition of GE's SCR
manual, Figure 12.6 shows exactly what you want. I was going to
scan it and post it, but it's copyrighted so I figured I'd better
not. Basically, it's a light dimmer with a thermistor placed in
parallel with the phase shift cap.
Professional circuit designer
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