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Registered Member #1213
Joined: Fri Jan 04 2008, 09:40PM
Location:
Posts: 14
Thanks for all replies. I also used ignition coil with dimmer, also tested 555 driver, it works very noisy. I think we can solve this problem by driving the ignition coil with pure sine wave. what does your experience say? is there any circuit for applying such voltage to the coil?any topology? can it solve the problem?
Registered Member #1596
Joined: Fri Jul 18 2008, 08:43PM
Location: USA
Posts: 65
mikeselectricstuff wrote ...
Capacitance on the output is a major problem for generating HVAC at flyback transformer type frequencies as even a few pf draws substantial power - this is why modern flybacks use funky tricks with diodes.
Could you tell, please what do you mean under "funky tricks with diodes" ? I am looking for the best way of getting a 10-30 kV DC. What capacitance are you mentioning?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
baleworker wrote ...
mikeselectricstuff wrote ...
Capacitance on the output is a major problem for generating HVAC at flyback transformer type frequencies as even a few pf draws substantial power - this is why modern flybacks use funky tricks with diodes.
Could you tell, please what do you mean under "funky tricks with diodes" ? I am looking for the best way of getting a 10-30 kV DC. What capacitance are you mentioning?
The "trick" is that the secondary is made of several sections, each section separated by diode. This greatly reduces the AC component on the windings which are at high potential, reducing the stress on winding-core insulation (this is why the transformers can be so compact; if there was just only 1 diode on the output, the transformer would die from corona quickly).
I think he meant secondary winding self-capacitance. Well, it does not draw any power, but acts as a parallel capacitor on the output and can excite unwanted resonances with square-wave drive (or any drive if you get near or above the resonant frequency formed by sec. capacitance and (leakage) series inductance(s)).
Registered Member #1596
Joined: Fri Jul 18 2008, 08:43PM
Location: USA
Posts: 65
Dr. Kilovolt wrote ...
The "trick" is that the secondary is made of several sections, each section separated by diode.
That sounds like an awesome idea and I keep dreaming of implementing it for the last few months. However I need a fullwave rectification for my SLR since it doesnt work well with half wave rectifier. Of cource I can do a center tap winding, but when it will waste 50% of the space and I will not be able to fit my windings on the core anymore. Anybody has any suggestions?
Registered Member #1213
Joined: Fri Jan 04 2008, 09:40PM
Location:
Posts: 14
in the link below you can find a well known HV flyback driver in Sam Barros' PowerLabs website.
in this page he speaks about producing 35KV even 40KV from old ac transformers. is it possible? if yes please explain "are these AC Flybacks designed to work in this High voltage or made to? I heard old flybacks have low High voltages only about 5 to 12 KV
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Masih wrote ...
in this page he speaks about producing 35KV even 40KV from old ac transformers. is it possible?
Well, his transformer is from old color TV which was used with no multiplier/cascade, so it is rated at 30kV. These transformers are extremely rare.
However, if you can find a robust transformer from a B/W TV or other TV (which contains AC transformer), it may be driven up to 30-40kV before it gets damaged. It only depends on the type/ruggedness/dimensions of transformer you get or find.
Registered Member #1448
Joined: Sat Apr 19 2008, 01:16PM
Location: Russia/Moscow
Posts: 21
Find old flyback from frist-generation color TVs You can find those in Russian color tvs RADUGA-703/RADUGA-704 Name of this flyback is "TVS-90LC2"(ТВС-90ЛЦ2 in Russian language), it can produce 24-25Kv AC from secondary and 10kv from primary
I currently have 3 flybacks(tvs-90lc2), i found one on scrapyard in color tv, and i bought 2 flybacks on last sunday at local radioshop just for 16$.I think there is MANY tvs-90lc2 in Russia, so it's not rare for me.
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AC High Voltage
