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Faulty temperature sensor

J

Jurgen Bauer

Jan 1, 1970
0
Hello,

I would like to check out a temperature sensor for my central heating
cylinder. 2 cables coming from the sensor.

What voltage do I need?
What should change with the rising temperature?

Thanks.
 
J

Jamie

Jan 1, 1970
0
Jurgen said:
Hello,

I would like to check out a temperature sensor for my central heating
cylinder. 2 cables coming from the sensor.

What voltage do I need?
What should change with the rising temperature?

Thanks.
i don't know but do you mean 2 wires or 2 cables?
there is a difference.
cables have 2 or more wires and even conductors
like drain wire.
wire on the other hand is a single conductor with
some kind of insulation around it.
in any case.
it's hare to say what type you have ?., could be a
Type-J, in many cases i have seen 2 sets of these types
wrapped around heating tubes.
only 1 needs to be used, in any case they are very small conductors
and mostly the J type which is 2 unlike metals twisted and electrically
bonded together.
the idea is when its heating one wire will contract more than the
other causing tension forces which produce a small amount of current to
the ratio of heat.
with these types you need a HI-Z micro volt meter to see the voltage
coming out of it.
some 10Meg-Z DMM's have a low scale that will read it.
under an ohm meter it will appear to be shorted.
--
now the RTD types ( Resistor thermo device).
that is basically a resistor that decreases in value
as the temp goes up. these was have 2 wires
---
then you have the IR (infra Red), where light is used to generate an
effect with a IR detector since temp produces IR in most cases that i
know of..
those comes in a different variety.. , modular types which require a
gnd, Vcc and 2 optional outputs.
some times it just a simple IR diode with a lens which only have 2
wires.
so take your pick..
P.S.
the Twisted Wire types normally use the same type of
material as the lead wire to the controller.
 
Å

ånønÿmøu§

Jan 1, 1970
0
i don't know but do you mean 2 wires or 2 cables?
there is a difference.
cables have 2 or more wires and even conductors
like drain wire.
wire on the other hand is a single conductor with
some kind of insulation around it.
in any case.
it's hare to say what type you have ?., could be a
Type-J, in many cases i have seen 2 sets of these types
wrapped around heating tubes.
only 1 needs to be used, in any case they are very small conductors
and mostly the J type which is 2 unlike metals twisted and electrically
bonded together.
the idea is when its heating one wire will contract more than the
other causing tension forces which produce a small amount of current to
the ratio of heat.
with these types you need a HI-Z micro volt meter to see the voltage
coming out of it.
some 10Meg-Z DMM's have a low scale that will read it.
under an ohm meter it will appear to be shorted.
Thanks for the detailed explanation. I'm working with a Micrel MIC280 and it
use a 2N3906 transistor junction as its remote sensor. Micrel has a demo
board and software that runs off a PC's printer port and you can set "high"
and "low" level trip points.

I'm working on a USB temp controller with multi-zone sensor inputs based
around the MIC280. Its been a fun project.
 
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