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Registered Member #952
Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388
A pair days ago I got this silly idea of an OLTC. Here's the block diagram:
Actually it isn't OLTC because it's not run "Off-Line", but the topology is otherwise the same. You may think the idea is silly, so do I I have built the 555 circuit already. I don't currently have time to throw the whole thing together. I don't except very good results from this circuit, but c'mon, it won't cost anything to try, and I have all the parts already. MOSFETs have never before been tested with OLTCs, there's a change it could even work with low powers. Next weekend I should have enough time to put it together. It could become DWOLTC, heh
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Guys, OLTC is pretty obsolete technology now, I don't think it's worth wasting your time.
25nF cap at that voltage is going to yield only 1.3milijoules at that voltage, absolutely no chance for any arcs.
To make any success out of OLTC, you will need to wind extremely low resonant frequency secondary, and use capacitors i uF range with a single turn primary. You'll need resonant frequency no higher than 100..200kHz.
What's the resonant frequency of your secondary spark?
In other words, don't build OLTC.
If you just want sparks from camera inverter, you are much better to simply discharge a few uF cap into a flyback.
If you want a TC, you'll be far, far better to simply build a small DRSSTC, and actually easier even if it doesn't look so. I'd really recommend you a small DRSSTC since it will be very good learning project, and very rewarding once you get it right!
Despite someone might tell you to increase size of your coil to lower the resonant frequency, don't do that - keeping the coil small really cuts the price of parts down, and small IGBT's can run up to a Mhz.
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Silly Miniature "OLTC"
I have built the 555 circuit already. I don't currently have time to throw the whole thing together. I don't except very good results from this circuit, but c'mon, it won't cost anything to try, and I have all the parts already. MOSFETs have never before been tested with OLTCs, there's a change it could even work with low powers. Next weekend I should have enough time to put it together. It could become DWOLTC, heh 
