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Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
The difference is that a "HOT" is a very low-gain, slow transistor, these are the design sacrifices needed for it to withstand high voltages. The driver in a TV effectively runs in Class-E, which can decrease switching losses. By adding the cap to C-E you are basically converting it to Class-E operation, but the antiparallel diode then becomes a must. Try increasing the voltage and *primary* turns even further, but decrease the feedback turns, actually 4 turns could be about right. Then, increase the value of the top resistor and decrease the bottom one, but not so much that the voltage divider puts out still over about 1V or so unloaded (otherwise the circuit won't start). As for the voltage, you can safely go to maybe some 120-150V, I've succesfully ran a self-oscillating HOT Class-E circuit at 320 volts, but it needs a lot of tuning and its on the verge of practical doability.
Registered Member #3926
Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525
Dr. Dark Current wrote ...
The difference is that a "HOT" is a very low-gain, slow transistor, these are the design sacrifices needed for it to withstand high voltages. The driver in a TV effectively runs in Class-E, which can decrease switching losses. By adding the cap to C-E you are basically converting it to Class-E operation, but the antiparallel diode then becomes a must. Try increasing the voltage and *primary* turns even further, but decrease the feedback turns, actually 4 turns could be about right. Then, increase the value of the top resistor and decrease the bottom one, but not so much that the voltage divider puts out still over about 1V or so unloaded (otherwise the circuit won't start). As for the voltage, you can safely go to maybe some 120-150V, I've succesfully ran a self-oscillating HOT Class-E circuit at 320 volts, but it needs a lot of tuning and its on the verge of practical doability.
I've adjusted the circuit by adding a resistor (2Ohms? I think) in parallel with the 33Ohm resistor I already have in the circuit, and now the power output is much more, the arc is now white and can stretch to 60mm~, This is without experimenting with primary turns and feedback, as the whole circuit is very shabby (I don't have solder) it's just some wires.
The resistors and HOT do get very hot now though, maybe the divider has lowered in voltage. I'll have to buy another multimeter this Friday, and solder.
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Single transistor flyback driver.
