thermister

[GregS]

I'm trying to reverse engineer this controller. I can't find anything yet on
its thermsiter. Its a 3 wire thermister, but the third wire
does no go to itself. It appears like two thermisters a 6 ohm and a 36 ohm series
combination. Top, bottom, and juncion. I'm trying to find a similar thermister. ??

greg

 

[Ecnerwal]

Its a 3 wire thermister, but the third wire does no go to itself.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
....what the heck is that supposed to mean? Not connected?

It appears like two thermisters a 6 ohm and a 36 ohm
series
combination. Top, bottom, and juncion. I'm trying to find a similar
thermister. ??

Are you quite sure it's a thermistor? There are other types of 3
terminal temperature sensors... If it is a thermistor, spelling it
correctly will yield better results when searching. "Dual Thermistor"
turns up quite a few results.

 

[GregS]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
....what the heck is that supposed to mean? Not connected?


Are you quite sure it's a thermistor? There are other types of 3
terminal temperature sensors... If it is a thermistor, spelling it
correctly will yield better results when searching. "Dual Thermistor"
turns up quite a few results.

Thanks, I'll try that. of course its K ohm.

greg

 

[legg]

I'm trying to reverse engineer this controller. I can't find anything yet on
its thermsiter. Its a 3 wire thermister, but the third wire
does no go to itself. It appears like two thermisters a 6 ohm and a 36 ohm series
combination. Top, bottom, and juncion. I'm trying to find a similar thermister. ??

Is it sealed in a vacuum?

How is it used in the circuit?

RL

 

[GregS]

Is it sealed in a vacuum?

How is it used in the circuit?

Its a black bead, pretty small. I don't yet know the circuit. It might be a
heated thermister.

One heater controller I made years ago, I simply used a thermister
driven with high current generating heat. If the liquid had dried up or vanished,
the heater would basically shut down automatically, because
the air could not dissipate the small amount of self generated heat.

greg

 

[Jim Thompson]

Its a black bead, pretty small. I don't yet know the circuit. It might be a
heated thermister.

One heater controller I made years ago, I simply used a thermister
driven with high current generating heat. If the liquid had dried up or vanished,
the heater would basically shut down automatically, because
the air could not dissipate the small amount of self generated heat.

greg

A bit scary... maybe... someone will lecture me on vapor pressure...

The typical automobile low-fuel indication is done using a self-heated
thermistor. When it no longer contacts fuel its self-heating causes
the resistance to plunge operating a relay ;-)

...Jim Thompson

 

[Joerg]

A bit scary... maybe... someone will lecture me on vapor pressure...

The typical automobile low-fuel indication is done using a self-heated
thermistor. When it no longer contacts fuel its self-heating causes
the resistance to plunge operating a relay ;-)

My old Chrysler had that for the oil level. All the cars I had since do
not have an oil level indicator at all. Only oil pressure and when that
lamp comes on it's often too late, meaning blue smoke coming out the
tail pipe.

 

[Jim Thompson]

My old Chrysler had that for the oil level. All the cars I had since do
not have an oil level indicator at all. Only oil pressure and when that
lamp comes on it's often too late, meaning blue smoke coming out the
tail pipe.

Real men don't own Chryslers ;-)

...Jim Thompson

 

[Joerg]

Real men don't own Chryslers ;-)

Well, my savings at the point when I received my degree were quite
miniscule. At least I didn't have any loan to pay back. But my trusty
old Citroen would not have passed the mandatory road worthiness test and
it also wasn't a "presentable" car. I mean, imagine picking up a
Japanese business visitor from the airport, him being in a fancy Armani
suit and me hopping out to crank the engine. It also leaked a bit when
it was raining. Oh, and it had Snoopy on his dog house painted onto the
side.

Hey, didn't you drive a Dauphine after receiving your masters? Ok,
that's a notch above the Citroen 2CV, had two more cylinders, but still ...

 

[Jim Thompson]

Jim Thompson wrote: [snip]

Real men don't own Chryslers ;-)

Well, my savings at the point when I received my degree were quite
miniscule. At least I didn't have any loan to pay back. But my trusty
old Citroen would not have passed the mandatory road worthiness test and
it also wasn't a "presentable" car. I mean, imagine picking up a
Japanese business visitor from the airport, him being in a fancy Armani
suit and me hopping out to crank the engine. It also leaked a bit when
it was raining. Oh, and it had Snoopy on his dog house painted onto the
side.

Hey, didn't you drive a Dauphine after receiving your masters? Ok,
that's a notch above the Citroen 2CV, had two more cylinders, but still ...

My money as a student was very much like yours. I bought the Dauphine
NEW when I was a junior at MIT for $1345 at Luby Chevrolet in Boston
;-)

Actually did keep it until I finished the Masters in 1968.

By then I also owned a 1964 Dodge Dart... oooops, that's a Chrysler
:-9

(My annoyance with Chrysler products derives from all the dud rentals
over quite a few years... now I specify NO Chrysler products.)

I then bought a 1966 Toyota Corolla and a 1967 Mercury Cougar.

...Jim Thompson

 

[Joerg]

Jim Thompson wrote: [snip]

Real men don't own Chryslers ;-)

Well, my savings at the point when I received my degree were quite
miniscule. At least I didn't have any loan to pay back. But my trusty
old Citroen would not have passed the mandatory road worthiness test and
it also wasn't a "presentable" car. I mean, imagine picking up a
Japanese business visitor from the airport, him being in a fancy Armani
suit and me hopping out to crank the engine. It also leaked a bit when
it was raining. Oh, and it had Snoopy on his dog house painted onto the
side.

Hey, didn't you drive a Dauphine after receiving your masters? Ok,
that's a notch above the Citroen 2CV, had two more cylinders, but still ...

My money as a student was very much like yours. I bought the Dauphine
NEW when I was a junior at MIT for $1345 at Luby Chevrolet in Boston
;-)

Then we had different priorities. After an oil rig summer job I spent
that kind of money on a bicycle. Custom frame, top notch shifters, the
works. Still have it. The Citroen was basically free, a basket case
where someone had messed up an engine overhaul. Fixed it, then drove it
for six years until it started losing stuff. The scariest was the sudden
loss of "cabin pressure" on an autobahn. I saw sparks flying in the
rear-view and almost froze. My trunk lid had come off and that was the
source of those sparks way back there ...

Actually did keep it until I finished the Masters in 1968.

By then I also owned a 1964 Dodge Dart... oooops, that's a Chrysler
:-9

The one with left-turn and right-turn lug nuts?

(My annoyance with Chrysler products derives from all the dud rentals
over quite a few years... now I specify NO Chrysler products.)

Same here. Gave my Chrysler to my brother when I had to buy a bigger car
to schlepp heavy lab gear. A year later he called me and said the car
went a bit nose up like an airplane during rotation. Followed by a
horrible noise. The rear right coil spring showed up in the rear-view,
inside the passenger compartment!

To me there were too many engineering bugs in that car. An aluminum
alternator bracket that always broke until I made one from steel. Or the
water pump that was prone to spectacular dumps until I found a Mercedes
pump I could somehow roach in there.

I then bought a 1966 Toyota Corolla and a 1967 Mercury Cougar.

Toyotas have been good to me.

 

[Jim Thompson]

Jim Thompson wrote: [snip]

[snip]

I then bought a 1966 Toyota Corolla and a 1967 Mercury Cougar.

Toyotas have been good to me.

I bought a 1977 LTD... it cured me of American cars.

More recent vehicles...

1977 280Z
1983 280ZX
1983 Sentra (x2, for the girls)
1986 Maxima
1996 Q45
2001 Frontier
2005 Q45

I'm about due for another middle-age moment and buy a sports car. I
understand that the Nissan "Z" car will return, totally re-designed
back to sports car size. I hope they put the 4.5L engine in it ;-)

...Jim Thompson

 

[[email protected]]

I'm trying to reverse engineer this controller. I can't find anything yet on
its thermsiter. Its a 3 wire thermister, but the third wire
does no go to itself. It appears like two thermisters a 6 ohm and a 36 ohmseries
combination. Top, bottom, and juncion. I'm trying to find a similar thermister. ??

Some people sold pairs of thermistors (with matching pairs of close
tolerance thin film resistors) to create a part that gave a roughly
linear resistance change with temperature over an appreciable
temperature range.

I remember buying and using such an assembly back in 1993, probably
from BetaTherm - ti cost too much for production (and anyway the
microprocessor could linearise a single thermistor) but was dead handy
for iniital experimentation.

This might be your device

http://www.betatherm.com/datasheets/PC344.php?pc_num=PC344&p_id=93

For some of the theory involved, this paper might help - I've not read
it in detail, but it looks as if it might be relevant

http://www.science-logic.net/renneberg-lehmann-ecctd07.pdf