EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: KJ-90 on June 10, 2017, 04:25:25 pm
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On the well-known Mike's Electric Stuff website, he has developed a driver circuit which works quite well with modern fly back transformers used in CRT television sets. The circuit is available here http://www.electricstuff.co.uk/marxgen.htm (http://www.electricstuff.co.uk/marxgen.htm) Beside the IRF830 MOSFET is 12nF 400V capacitor, paralleled by a 150V Zener diode. I was wondering what the 12nF 400V capacitor does. I believe the 150V Zener diode is to protect the circuit from a strong back EMF effect. What would happen if a larger or smaller capacitor was used in place of the 12nF unit?
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The capacitor forms a resonant circuit, recycling the unused energy otherwise wasted in the snubber of a conventional flyback circuit.
The operation is described here:
https://www.repairfaq.org/sam/deflfaq.htm#dshdf (https://www.repairfaq.org/sam/deflfaq.htm#dshdf)
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+1 for resonant circuit. Perhaps its time for Dave to do a fundamentals video on the basic tuned oscillator/amplifier circuit.