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Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Has anyone tried cutting the top off a 2N3055, spraying it with a thin layer of varnish, and running it under water? It would take some serious power to get the die temperature much higher than 100C.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
I have opened and run one under water to cool it when we were doing the 3055 as LED thing, it was already covered in some sort of varnish. It seems there are a few different 3055 designs with different size dies and contents. One of those I opened emitted a strong smell of alcohol/solvent.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Bjørn wrote ...
I have opened and run one under water to cool it when we were doing the 3055 as LED thing, it was already covered in some sort of varnish. It seems there are a few different 3055 designs with different size dies and contents. One of those I opened emitted a strong smell of alcohol/solvent.
From Wikipedia:
"With changes to semiconductor manufacturing technology, the original process became economically uncompetitive in the mid 1970s, and a similar device was created using epitaxial base technology.[1] The maximum voltage and current ratings of this device are the same as the original, but it is not as immune from secondary breakdown; the power handling (safe operating area) is limited at high voltage to a lower current than the original.[1] However, the cut-off frequency is higher, allowing the newer type of 2N3055 to be more efficient at higher frequencies. Also the higher frequency response has improved performance when used in audio amplifiers.[1]"
Then there is the 2N3055E and 2N3055H. I have been told that Motorolla ones, from their factory in Mexico, are reputed to be the best.
EDIT: apparently, the 2N3055 is epitaxial base, while the 2N3055H is hometaxial base, which increases it's resistance to secondary breakdown..
The 2N3055H has a max. frequency of 0.8 mHz, while the 2N3055E has a max. frequency of 3 mHz., while the 2N3055 and2N3055G (lead free) has a max. frequency of 2.5 mHz.
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Probably the world's most labour intensive 2N3055 air-cooled heatsink
