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Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Thanks for your excellent advice on flyback drivers, Antonio
The single transistor self-oscillating circuit is one of these things that looks simple, but actually has a lot going on. I thought I understood it until I read some of Antonio's previous posts on the subject, that also explained some weird results I was getting with a Joule Thief-style LED driver.
A separate oscillator is more complex to build, but easier to operate, because it doesn't have non-linear feedback mechanisms ready to do weird stuff.
Finally, I heard that some flybacks actually can't store much inductive energy by themselves. In the TV, they have the deflection coils connected in parallel with them, and most of the energy for the flyback pulse is actually stored in these. A flyback of this kind would obviously work much better if you salvaged the yoke along with it, or used a bridge-type driver that doesn't rely on stored energy.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
The horizontal deflection transistors are not completely useless. I could easilly use them in this scheme as a direct substitution of the mosfet but the 9A UCC gate driver is necessary prerequisite. There was no extra heating, however the FETs are better
Here is the device (same scheme) where the NPN deflection transistor is already installed and is powering an iginition coil at 6KHz straight from the mains (sucking 400W....)
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Determining A Useful Transistor
