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Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Here is an oscillator circuit I dug up
I can use a DIAC to send a startup pulse to the lower transistor base to get it to conduct and start oscillations. I was hoping someone could clear up what prevents both transistors from simultaneously being in a conducting state, rather than switching back and forth.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
A royer push-pull oscillator? I am thinking the phasing of the transformer coils is responsible for allowing only one transistor to conduct at one time. I found a close circuit on the HvWiki, but no good explaination of one cycle.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Honestly, Smoothie,. there's so few parts I'd just patch it together on the bench. and see how it goes. But I'd call it a kind of multivibrator - or push-pull gismo as you suggest - for want of better knowledge.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
Although not shown in the circuit diagram I assume that the two transistors are driven by the feedback windings - and one phase will be inverted with respect to the other.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
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Posts: 1567
Would this be a good transistor to drive the oscillator ?
I need something with a high breakdown voltage. (450v) It should handle 8-10A. (30A) It should have a high gain (on page 4/8 it appears to have a gain between 10 and 20 for most of the range). Fast switching.
I would just like it if someone could verify if this is a good choice.
Registered Member #142
Joined: Sat Feb 11 2006, 01:19PM
Location:
Posts: 102
Smooth, obviously the bases get driven 180 degrees out of phase. If one gets driven on, the other must necessarily get driven off at the same time. Looks pretty fail-safe on the face of it, just have to see what happens on the bench. I would note that you could probably replace the current transformer with a couple of feedback windings on the output transformer. Building an induction heater?
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transistor oscillator
