Hi,

Our vintage aircraft are operated with an appr. 50 year old
oiltemp.gauge. Alas the sensorprobes have all failed.
In a test setting it was determined that the probe was of a PTC type
with the following characteristics;
T( in Celcius) R (Ohm)
120 151
110 145
100 138
90 134
80 129
70 124
60 119
50 113
40 108
30 99
10 95
We haven't been able to find a PTC sensor yet, anyone out there with a
good advice, because we would like to go on with the original
instrument,

thanks

Michiel

www.seagull-formation.nl

Post this over on rec.aviation.owning to get an answer.

"Seagull149" wrote in message
ups.com...
Hi,

Our vintage aircraft are operated with an appr. 50 year old
oiltemp.gauge. Alas the sensorprobes have all failed.
In a test setting it was determined that the probe was of a PTC type
with the following characteristics;
T( in Celcius) R (Ohm)
120 151
110 145
100 138
90 134
80 129
70 124
60 119
50 113
40 108
30 99
10 95
We haven't been able to find a PTC sensor yet, anyone out there with a
good advice, because we would like to go on with the original
instrument,

thanks

Michiel

www.seagull-formation.nl

"Seagull149" wrote in message
ups.com...
Hi,

Our vintage aircraft are operated with an appr. 50 year old
oiltemp.gauge. Alas the sensorprobes have all failed.
In a test setting it was determined that the probe was of a PTC type
with the following characteristics;
T( in Celcius) R (Ohm)
120 151
110 145
100 138
90 134
80 129
70 124
60 119
50 113
40 108
30 99
10 95
We haven't been able to find a PTC sensor yet, anyone out there with a
good advice, because we would like to go on with the original
instrument,

thanks

Michiel

www.seagull-formation.nl


You might try the " components " forum on www.elektor-electronics.co.uk

This is just the sort of challenge that readers of Elektor Electronics
magazine like, and as an added bonus, the magazine is based in your homeland
of Holland. Get it sorted, and you can probably get some extra publicity for
your group by writing an article for the mag on how you solved your problem
( assuming you do ... )

Arfa

On 17 Feb 2006 07:09:29 -0800, "Seagull149" put
finger to keyboard and composed:

Hi,

Our vintage aircraft are operated with an appr. 50 year old
oiltemp.gauge. Alas the sensorprobes have all failed.
In a test setting it was determined that the probe was of a PTC type
with the following characteristics;
T( in Celcius) R (Ohm)
120 151
110 145
100 138
90 134
80 129
70 124
60 119
50 113
40 108
30 99
10 95
We haven't been able to find a PTC sensor yet, anyone out there with a
good advice, because we would like to go on with the original
instrument,

thanks

Michiel

www.seagull-formation.nl

I notice that the characteristic is mostly linear, excepting for
possible typos at the lowest two temps. Maybe you could adapt an IC
temperature sensor and use its output to drive a current sink. Or you
could take the output of *any* resistive temp sensor and use a PIC
micro to translate the resistance values via a lookup table. The PIC's
output could then drive a cheap 8-bit IC DAC or an R-2R DAC, which
would in turn drive a current sink for the gauge.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Sat, 25 Feb 2006 21:00:30 +0000, "Neil J. Harris"
put finger to keyboard and composed:

HI,
could it be an ordinary 100 Ohm PRT, 100 Ohms at 0 Deg.C and 138 Ohms at
100deg.C etc.?
I don't have the tables to hand but I will check on Monday.

Looks plausible, depending on the accuracy of the OP's measurements:
http://www.thermometricscorp.com/plt100ohm0c0.html


In message , Franc Zabkar
writes
On 17 Feb 2006 07:09:29 -0800, "Seagull149" put
finger to keyboard and composed:

Hi,

Our vintage aircraft are operated with an appr. 50 year old
oiltemp.gauge. Alas the sensorprobes have all failed.
In a test setting it was determined that the probe was of a PTC type
with the following characteristics;
T( in Celcius) R (Ohm)
120 151
110 145
100 138
90 134
80 129
70 124
60 119
50 113
40 108
30 99
10 95
We haven't been able to find a PTC sensor yet, anyone out there with a
good advice, because we would like to go on with the original
instrument,

thanks

Michiel

www.seagull-formation.nl

I notice that the characteristic is mostly linear, excepting for
possible typos at the lowest two temps. Maybe you could adapt an IC
temperature sensor and use its output to drive a current sink. Or you
could take the output of *any* resistive temp sensor and use a PIC
micro to translate the resistance values via a lookup table. The PIC's
output could then drive a cheap 8-bit IC DAC or an R-2R DAC, which
would in turn drive a current sink for the gauge.

- Franc Zabkar

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.