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Old 13th December 2004, 11:03 PM   #1
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Default power dissipation

how much power can i dissipate from a SINGLE transistor??
I mean to-3 case (probably best), huge (but not active) heatsink
cheers
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Old 13th December 2004, 11:25 PM   #2
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Check the datasheet.

Most TO-3's are in the 50 to 150W range.

The specification states that the case is kept at room temperature (25ÝC), which realistically means either very short duration use (essentially pulsed) or water cooling. A large heatsink with a few hundred watts might hold 25 above 25ÝC (or 40 in Australia ), or 50-65ÝC absolute.

If there isn't a graph of it, there's a derating spec which usually goes from say, 150W at 25 down to 0W at 175ÝC, so say 75W at 100ÝC. With good thermal contact you can assume the case is the same temp as the heatsink (plus a few degrees, you should be able to find some specs for conductivity of insulators and stuff).

Tim
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Old 14th December 2004, 03:08 PM   #3
AndrewT is offline AndrewT  Scotland
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Hi,
the highest TO3 power rating I have seen is 250w.
This is only at or below 25degrees C case temperature.
I think you could only achieve this with water cooling.
regards Andrew T.
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