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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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26th Aug 2018, 11:15 pm | #1 |
Hexode
Join Date: Feb 2010
Location: Hull, East Riding of Yorkshire, UK.
Posts: 315
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Bakelite Thermometer by Gossen
Hi guys picked this up at a carboot complete with original thermocouple.
It takes a 1.5v cell and when the battery is inserted it does have meter deflection etc but i don't think any of it is related to actual temperature be that ambient without the probe or with the probe, unfortunately the text explaining its operation has rubbed off, any help would be greatly appreciated. it has 4 different modes as shown in the photo the only one i really understand is battery disconnected. Could a passing mod please edit my terrible title spelling. much thanks |
26th Aug 2018, 11:16 pm | #2 |
Hexode
Join Date: Feb 2010
Location: Hull, East Riding of Yorkshire, UK.
Posts: 315
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Re: Bakelite Thermotmeter by gossen
hope this is the last image.
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26th Aug 2018, 11:48 pm | #3 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
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Re: Bakelite Thermotmeter by gossen
The modes look like
Range 1 Range 2 Set pointer to red mark on scale OFF
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27th Aug 2018, 12:09 am | #4 |
Hexode
Join Date: Feb 2010
Location: Hull, East Riding of Yorkshire, UK.
Posts: 315
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Re: Bakelite Thermotmeter by gossen
Any ideas how one would set the pointer to that level it seems to fully deflect to the left on that setting
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27th Aug 2018, 1:06 am | #5 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
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Re: Bakelite Thermotmeter by gossen
What happens if you adjust that other control you have shown?
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27th Aug 2018, 1:16 am | #6 |
Banned
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
Posts: 2,704
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Re: Bakelite Thermotmeter by gossen
I have one of these!! To set the red pointer you use the magnetic correction knob at the bottom of the unit. The first switch position is used to set "zero" on the red mark as my pic shows. The magn. Corr. knob will rotate many times, end to end so it may take "quite a few turns" to zero the meter to the calibration mark.
The first range will show "normal" temperatures, but the second scale is for 90 degrees + so unless the temp is above this figure, the meter will pin to the left. It is a beautiful instrument, and very accurate. Be very careful of the probe!! it is very sensitive temperature wise. |
27th Aug 2018, 1:36 am | #7 |
Hexode
Join Date: Feb 2010
Location: Hull, East Riding of Yorkshire, UK.
Posts: 315
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Re: Bakelite Thermotmeter by gossen
Nothing sadly it also has. No stop just. The resistance In turning increases. I think I need to get it open
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27th Aug 2018, 4:10 am | #8 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: Bakelite Thermotmeter by gossen
It's too old, I think, to have a fancy semiconductor cold temperature compensator, so it has an adjuster which needs setting to get a known temperature to read correctly, else the reading will vary with the temperature of the cold junction. (If you have a circuit with two dissimilar metals, you inevitably have two junctions with thermoelectric potentials opposing so a simple meter would read the temp difference between junctions).
The offset scale is probably why it has a battery. The pointer going left on the set-to-red-dot range could be the batteries in the wrong way round. It's worth checking, the markings may be unclear. David
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