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View Full Version : Help with Thermistor Circuit



CocaColaKid
- 11th May 2005, 19:17
I'm looking to use a thermistor to measure temperature and have no clue how to actually setup the support circuitry. I've read about a bridge and another way about using an op-amp to linearize the output but for the most part this is greek to me. Any help / schematics would be greatly appreciated. I'm currently using a DS1820 but the price is kind of high and I can't go much further than 5 feet from the PCB before the sensor dies.

Luciano
- 11th May 2005, 23:03
I'm currently using a DS1820 but the price is kind of high
and I can't go much further than 5 feet from the PCB before the sensor dies.Only 5 feet?

From URL: http://www.phanderson.com/tm125.html
In theory, up to 256 DS18S20 temperature sensors may be accommodated on the single twisted pair.
However, the limiting factor is the capacitance and my suggestion is up to sixteen DS18S20 devices
on a maximum of 200 feet of twisted pair cable.

* * *
The price is high but if you need a remote temperature sensor the DS18S20 is
a good solution. You need only a twisted pair cable. No power supply needed
for the sensors (parasite power). Range -55 to +125Deg C.
No calibration required! (Calibration = $$$$).

Best regards,

Luciano

Stump
- 12th May 2005, 07:08
try LM335
you can read it directly on the a/d without any support
it is quite inexpensive
it is very linear
uses 2 wires
is readily available
You will only be able to linearize a thermistor over a small range
(0-50deg c) with marginal results