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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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Old 13th Oct 2020, 10:40 am   #1
Backtoreality
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Default STC YBA020TB thermistor

Hi folks,

I need a thermistor for a Ni-Cd charging circuit. The component list says its an STC YBA020TB but I can't seem to find one listed or any information about the spec. Has anyone got any info that would help me source a replacement?

David
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Old 14th Oct 2020, 11:41 am   #2
orbanp1
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Default Re: STC YBA020TB thermistor

Hi David,

If you posted the circuit (it seems you have it) then people would be able to help you to figure what value thermistor would work there.
Then one could pick an available replacement.

Regards, Peter
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Old 16th Oct 2020, 9:53 am   #3
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Default Re: STC YBA020TB thermistor

Hi Peter, the thermistor sits within the battery pack and the circuit is just a partial hand drawing. I've filed the corrosion off the soldered connections and measured the resistance. It's 50 ohms initially and goes up to 70 ish ohms as I hold the probes on it. I'm wondering if I can just solder wires on to it? Photo attached.
David
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Old 16th Oct 2020, 12:57 pm   #4
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Default Re: STC YBA020TB thermistor

Hi David,

Interesting!
Thermistors are usually NTC! Not that there no PTC thermistors, there are those around too!
You could try soldering to it, but how durable would it be?
Would you want to trust the safety of charging to that?
As an alternative, and probably I would pursue that, is to trace out the charger circuit, those are usually quite simple if it is an older charger/battery pack, and from that you could assess the role and possible value of the thermistor in the pack.
Also, if you have another battery pack, with an intact thermistor, you could use that to identify the component.

Regards, Peter

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Old 18th Oct 2020, 6:51 am   #5
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Default Re: STC YBA020TB thermistor

I've looked in the bumf I have and online and all I found is an earlier STC datasheet that covers glass bead types on a thread from this forum. I do have a Murata PTC datasheet but am pretty sure it doesn't cover your thermistor.

Thermistors seem to share a very similar convention where letters and numbers mean the same thing, to a point, but I couldn't find a YBA or TB anywhere.

"I'm wondering if I can just solder wires on to it" You've nowt to loose, use a very hot iron with very short dwell time, this works on batteries.

Andy.
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