Electronics > Projects, Designs, and Technical Stuff
High Frequency DC High Voltage Arc Ignition Generator Inverter Boost Step-Up ??
cpuxxx:
i didnt understand flyback - feedback relationship here clearly. Normally a driver switches here transistor's gate but in here what switches transistor's gate ? Gate is closing and opening so fast as polarized by coil or something like that ? What switches here transistor's gate ?
strawberry:
I have this plug and play ZVS flyback multifunktion driver up to 240W rated output (ATX compatible): eBay auction: #303152318527 and flyback transformer as well eBay auction: #302204237459
Your circuit is similar to '' joule thief circuit ''
floobydust:
Here is a schematic of the "15kV generator" kit with more details.
I think it's better mostly a saturated-core oscillator, as I understand how it operates:
Initially, the transistor gets base-current through the feedback winding and turns on.
Flux in the core increases and the feedback winding generates (in-phase) EMF to assist and add base-current.
Current ramps up until the flux no longer can build up- either the core saturates OR the transistor plus winding resistance plus battery reach their maximum current. The flux density is no longer increasing.
Then the feedback winding generates no EMF, and the transistor turns off slightly.
Any drop in flux density causes the feedback winding to generate opposition (counter EMF) to base-current which turns off the transistor, until the flux falls to nothing and the cycle repeats.
I did not measure the core's saturation point yet on these cores, I did not see an air gap.
I find these kits have crappy counterfeit transistors which tend to run pretty hot.
David Hess:
That configuration is called a blocking oscillator and it is essentially one half of a Royer oscillator which operates in the same way but with two transistors in a push-pull configuration.
Drive to the base of the transistor is controlled by the *change* in flux in the core of the inductor. When the core saturates and the flux stops increasing, the base drive is removed and the transistor turns off. The decreasing flux in the core then pulls the base negative holding the transistor off until the flux through the core drops to zero and stops decreasing.
Tektronix made great use of blocking and Royer oscillators for the high voltage inverters in their oscilloscopes through to the 1980s.
floobydust:
I'm not sure what the name of this type of oscillator is because some use an RC delay and not core saturation. So I use different names. Or maybe it doesn't matter.
People seemed to come up with an oscillator, patent it and use their name for it:
1937 blocking oscillator patent is about the tuning capacitance.
1951 transistor blocking oscillator patent
1957 Triggered transistorized blocking oscillator with saturable transformer
Royer has an extra inductor and I only know of it being push-pull, near sinusoidal not flyback.
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