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Banned on 1/22/2011 for repeated rule violations after multiple warnings. Registered Member #3299
Joined: Sat Oct 09 2010, 08:11PM
Location: Bantown, USA
Posts: 220
make banks of them in series parrelel, and a zvs on rectified mains
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
you can run BJTs in parallel as long as you put sharing resistors in the emitters I recently serviced some antique equipment at work that used large banks of 2N3055 type transistors in parallel (I forgot the exact part number) and the emitter sharing resistors were what looked like springs, just coils of stiff wire.
I have been in a similar situation before with parts, and I just stick them into a drawer and forget about them for 10 years 10 years later I have so much stuff I can't move
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Mads Barnkob wrote ...
put 30 in series and make a filtered MOT supplied single switch SSTC
I assume this was a joke, but just in case, this will not work. A rectified MOT would provide around 3kV, 30 in series would handle about 3kV, but for a single switch SSTC, you would want a switch that could handle many times the DC supply voltage. Secondly, you would need to provide 60 insulated gate drive signals. Lastly, these are low speed switching transistors, and they would not work very well at SSTC frequencies.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Anders M. wrote ...
Mads Barnkob wrote ...
put 30 in series and make a filtered MOT supplied single switch SSTC
I assume this was a joke, but just in case, this will not work. A rectified MOT would provide around 3kV, 30 in series would handle about 3kV, but for a single switch SSTC, you would want a switch that could handle many times the DC supply voltage. Secondly, you would need to provide 60 insulated gate drive signals. Lastly, these are low speed switching transistors, and they would not work very well at SSTC frequencies.
It was a joke to throw oneself into making a driver for that :)
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60 TIP-122's
I recently serviced some antique equipment at work that used large banks of 2N3055 type transistors in parallel (I forgot the exact part number) and the emitter sharing resistors were what looked like springs, just coils of stiff wire.
10 years later I have so much stuff I can't move 
