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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 12th Jun 2018, 9:25 pm   #1
MrBungle
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Default What can I replace a dead stabistor with?

I have a 15v stabistor in a design I want to replace. Can anyone confirm the function of these. I assume that they forward conduct at 15v and do not reverse conduct at all unlike a Zener. Would a 14.3v Zener and 1n4148 back to back do the job?
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Old 12th Jun 2018, 10:44 pm   #2
McMurdo
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Default Re: What can I replace a dead stabistor with?

The only ones I've come across have been in thermal tracking for bias stabilisation in audio output stages. They are, AFAIK, made of multiple stacked silicon junctions up to the specified forward voltage and are used forward biased to track the output devices.

The ones I've seen were rated at a Vf of around 4V and I used a chain of SMD rectifier diodes to obtain the right reference for the job. 15V obtained this way might be a bit ambitious!

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Old 12th Jun 2018, 10:57 pm   #3
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Default Re: What can I replace a dead stabistor with?

Thanks for the info. That’s what I looked at doing first and decided I didn’t fancy it

This is used as a voltage clamp in a regulator’s foldback control.
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Old 12th Jun 2018, 11:07 pm   #4
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Default Re: What can I replace a dead stabistor with?

If it's not for thermal tracking then I suppose your suggested way is OK. A reverse biased zener is apparently not a good idea for emulating another forward biased junction!
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Old 14th Jun 2018, 4:28 pm   #5
MrBungle
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Default Re: What can I replace a dead stabistor with?

I’ve tested it now. Seems to work fine. Purely by chance I came across the same circuit being used in the LT1073 switching regulator data sheet as well.
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