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| Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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20th May 2023, 8:09 am
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#1 |
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Triode
Join Date: Nov 2015
Location: SE London, UK.
Posts: 24
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Vintage Thermistors
The Thermistor shown below I removed from a transistorised Tripletone amplifier which I'm reverse engineering, i believe these were made by Mullard, if anyone can correct me. It measures 1.3k ohms across the pins and this seems to tally up against a resistor colour chart and he resistance also decreases in value after warming slightly so obviously a NTC, where as this one appears in good condition that is not the same to be said for the other channel where it has swollen and split.
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20th May 2023, 8:50 am
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#2 |
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Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
Posts: 4,992
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Re: Vintage Thermistors
The Mullard colour codes are a mysterious thing.
The zero power resistance is read from the bottom. So brown orange red - which is 1300 ohm at 25C and there is a +/-20% tolerance. It is a negative temperature coefficient - so resistance goes down as it gets hotter. The temperature characteristic is described by its use as a temperature sensor, or in a self heating mode. All this stuff, and how to interpret the data is in the Mullard Technical Handbook Book 3 (Components, materials and assemblies) part 1 (Capacitors, Resistors), 1980. I have no idea where I downloaded all this stuff, but give me your email address by PM and I'll send it (it is 11MB of pdf) Craig
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Doomed for a certain term to walk the night |
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20th May 2023, 9:38 am
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#3 |
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Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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Re: Vintage Thermistors
Hi Craig, would it be worth asking one of the mods to put on the forum as a sticky?
Ed |
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20th May 2023, 9:49 am
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#4 |
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Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
Posts: 4,992
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Re: Vintage Thermistors
Found them! https://worldradiohistory.com/Archiv...Suppliers/MNO/
All the Mullard Technical Handbooks are there. Craig
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20th May 2023, 10:35 am
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#5 |
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Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Vintage Thermistors
The one in the photo looks like a VA1038:
http://www.electrojumble.org.uk/DATA...o%20VA1040.pdf Lawrence. |
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20th May 2023, 10:36 am
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#6 |
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Pentode
Join Date: Nov 2020
Location: Bristol, UK.
Posts: 132
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Re: Vintage Thermistors
Probably a Mullard VA1077 which is used for AC128/AC176 and AD161/AD162 complementary pairs
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20th May 2023, 10:49 am
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#7 |
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Triode
Join Date: Nov 2015
Location: SE London, UK.
Posts: 24
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Re: Vintage Thermistors
Thanks, hopefully then i should find a suitable replacement
 Peter |
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20th May 2023, 11:45 am
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#8 | |
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Dekatron
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,621
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Re: Vintage Thermistors
Quote:
It’s definitely a VA1038 (red, orange, brown stripes). Last edited by dazzlevision; 20th May 2023 at 12:02 pm. |
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