Author Topic: why to run transistors hot?  (Read 1806 times)

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Offline strawberryTopic starter

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why to run transistors hot?
« on: November 25, 2021, 10:29:45 pm »
what is benefit
 

Offline fourfathom

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Re: why to run transistors hot?
« Reply #1 on: November 25, 2021, 10:36:19 pm »
Not needing to use a larger transistor?  As long as you have a comfortable margin there's no reason not to run a transistor a bit hot.  True, elevated temperatures accelerate device degradation, but normal "hot" operation isn't hot enough to make a big difference.
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 

Offline John B

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Re: why to run transistors hot?
« Reply #2 on: November 25, 2021, 10:39:05 pm »
Uh, could we quantify these with some numbers?
 

Offline fourfathom

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Re: why to run transistors hot?
« Reply #3 on: November 25, 2021, 10:53:43 pm »
Uh, could we quantify these with some numbers?

Ask a squishy question, get a squishy answer.
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 

Offline mc172

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Re: why to run transistors hot?
« Reply #4 on: November 25, 2021, 11:06:38 pm »
what is benefit

They don't ever ask you to turn the heating on?
 

Offline Gregg

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Re: why to run transistors hot?
« Reply #5 on: November 26, 2021, 12:10:13 am »
Delta T: the hotter they are, the more heat they dissipate.  :=\
 

Offline Brumby

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Re: why to run transistors hot?
« Reply #6 on: November 26, 2021, 12:38:05 am »
With the information given, this is one of the better answers one could ever expect:
Not needing to use a larger transistor?  As long as you have a comfortable margin there's no reason not to run a transistor a bit hot.  True, elevated temperatures accelerate device degradation, but normal "hot" operation isn't hot enough to make a big difference.

After all, they just need to survive long enough to pass any warranty period - and any statutory "fit for purpose" requirements.

Anybody offering high reliability products will try and reduce the operating temperature as much as possible.
 

Offline fourfathom

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Re: why to run transistors hot?
« Reply #7 on: November 26, 2021, 01:50:00 am »
Anybody offering high reliability products will try and reduce the operating temperature as much as possible.

As much as practical.  You're not going to add a cryo-cooler unless necessary.  When I think "hot", it's more like warm to the touch, but not uncomfortably so.  Once it gets painful then you need to know what you're doing, and knowing theta junction/case (and other specs) is critical.
We'll search out every place a sick, twisted, solitary misfit might run to! -- I'll start with Radio Shack.
 

Offline strawberryTopic starter

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Re: why to run transistors hot?
« Reply #8 on: November 26, 2021, 05:03:51 pm »
modern electronics yes, after two y buy new one

but HP, Tektronix ..  metal can transistors can withstand higher heat but still why
 

Offline Miyuki

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Re: why to run transistors hot?
« Reply #9 on: November 26, 2021, 05:12:12 pm »
modern electronics yes, after two y buy new one

but HP, Tektronix ..  metal can transistors can withstand higher heat but still why
You rarely want to go near the plastic mould temperature limit of 150-175°C, metal or ceramic parts can go higher, but not much when it is just a plain silicone
 


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