high voltage 555 audio modulated flyback


Posted on Feb 6, 2014

I bricked my iPod shuffle, seems that the controller chip for the mini jack got wasted as it could no longer detect charger, PC connection or play music as it could not detect headphones. The arc have to be very short in order to limit the distortions of an unstable arc. The sound quality is low due to the way the audio modulation is implemented. There are


high voltage 555 audio modulated flyback
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basically 2 kinds of modern flybacks, television flybacks are driven near 15kHz and monitor flybacks are driven between 30-150Khz. Depending on which type we use, we have to adjust the frequency of the 555 timer to match the resonance of the flyback for maximum performance. The voltage rating of the MOSFET (VDSS) needs to be 6 to 10 times higher than the supply voltage, reverse voltage spikes and EMF can be high enough to destroy the MOSFET if its too small. But we still need to use MOSFETs with a reasonable low on resistance (RDS(on). Try to find a MOSFET with a RDS(on) value not much higher than 0. 1 ohm, if you have problems try one with a lower RDS(on) value. Protect against surge voltages on the MOSFET gate, effectively this would require a much higher resistance, a high gate resistance would lower the operation speed significantly. The values of a gate resistor could be anything between 10 ohm to 200 ohm, it all depends on the MOSFET, experimentation is needed. The alternative is complicated calculations involving data that is usually not available in standard data sheets. Pin 5 on the 555 timer is a direct access to the upper voltage comparator in the 555 timer. This allows us to pulse width modulate the output on pin 3 of the 555 timer. I wanted to do a audio modulated flyback arc with few components and a small form factor. I installed the MOSFET on a old CPU heat sink with fan, the 555 timer circuit is also...




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