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 Post subject: Ring Choke Converter(RCC) For vacuum tube amplifier?
PostPosted: Jan Fri 10, 2020 10:49 am 
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Joined: Jan Fri 03, 2020 7:54 pm
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Location: Malaysia Penang
rcc_1.jpg [ 184.04 KiB | Viewed 453 times ]

Hi forum,
Just to share i have build RCC several month ago. I build Flyback converter , Half bridge , Full bridge with PWM controller chip. I saw there is alot cheap USB charger using a single transistor to work as flyback, They look very similar to Blocking oscillator. I'm wonder can i build similar power supply for power tube amplifier? Now a days PWM controller chip is not expansive such as UC3845 they work great as flyback . This project just for education learning purpose. Do not try this if you dont have experience to handler high voltage and This project can be dangerous. I do no responsible for any injury.

I take the challenge to build RCC with TO-220 13007 BJt transistor. My house main voltage is about 230VAC which after rectifier the voltage go up 320VDC, and 13007 VCEO max is 400V (actually it did work for 430V, i not sure maybe will reduce life span) . SO i only have 80V headroom for Flyback reflect voltage. So i choice 30V as reflect voltage.output 250VDC and 6.3VDC for power a 6P1(6AQ5/6V6) and 6J1(6AK5/EF95) as mono block tube amplifier. The transformer core is EI33 primary wind 30turn 0.37mm magnetic wire, secondary for 250V output i wind 250turn 0.15mm magnetic wire, and 6.3V output 6turn with 0.5mm magnetic wire. The feedback winding is 12 turn 0.37mm wire . My target is to power a mono tube amplifier, they work well after 2hours i measure the transistor , the temperature raise up 60C , The converter work as Fix on duty cycle and vary the off duty cycle length for modulation. The simple regulation is through UF4007 charge up 10uF during turn off period(flyback time) capacitor when capacitor having -12V the 12V zener and turn off the 13007. Since the feedback coil have 12 turn regulate with -12V , and it also reflect the secondary with 250turn having 250V output and 6 turn for 6V output . This circuit is not work very great , i just take challenge to minimize the component and try to make it as simple as possible.

when i try to power stereo 2 of 6P1 and 2 of 6J1, the transistor burn within 5minutes and E and C shorted.

Overall schematic as below:
RCCSCH.jpg [ 122.35 KiB | Viewed 453 times ]

Video :

For detail i have write down in my page for recording purpose: ... r-as-load/

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