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Registered Member #3451
Joined: Sun Nov 28 2010, 11:13PM
Location: United States
Posts: 100
The 2N3055 page at RadioShack ( has a few reviews which seem to be saying that this transistor doesn't work very well for HF flyback drivers. If this is the case, then why is the 2N3055 recommended for this purpose on HvWiki and PowerLabs? I understand that that the single transistor driver is relatively low power, but is there a better alternative?
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
There are plenty of better alternatives.
Most 2N3055's are recommended for up to 2.5-3MHz, but realistically are limited to around 1MHz.
In my opinion they are fine for in excess of 20kHz, (100kHz should be ok too). They were extensively used as power amplifiers in audio amplifiers so have good response over the audible frequency.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
smcerm wrote ...
The 2N3055 page at RadioShack ( has a few reviews which seem to be saying that this transistor doesn't work very well for HF flyback drivers. If this is the case, then why is the 2N3055 recommended for this purpose on HvWiki and PowerLabs? I understand that that the single transistor driver is relatively low power, but is there a better alternative?
Because the 2N3055 is a "classic" power transistor. It has a horrible package and poor ratings. I'd suggest a Royer-based driver.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Two words. Gain, and BJT. BJTs are lossy if driven without proper voltage/bias, as at least some are meant for linear devices like regulators or linear amps.
It is also low gain, so it takes alot of power to turn it on hard enough to prevent it from dissipating much heat.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
smcerm wrote ...
Hm, thanks. Can a power MOSFET be used in place of the 2n3055?
The circuit becomes a bit more complicated. Most people use a 555 or TL494 to drive the gate, I think. There are a few simple designs on here and on other websites. I can't remember offhand who's though.
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2N3055 not suitable for High Frequency?
