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Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
I was working on a small Tesla coil for awhile until I got around to the power supply, I never got the one I planned and I need to find an alternative. I was thinking about buying two nice big flybacks from eBay or some other internet store and putting them in parallel, I will use a ZVS flyback driver to power them and submerged the flybacks in mineral oil to insulate/ cool them. I use “Tesla coil CAD version 2.0†to calculate my coils and I want to know the flyback voltage output and current output in parallel and I have no clue how to do so. So any help would be appreciated.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
You should wind your own ferrite transformer; they stand up to high power better. A single-layer secondary is not that hard to to, and can (probably) do 10KV if done right. Even 5 or 6 KV is enough for an SGTC.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
I thought I need to know the output so i calculate the capacitor. What do you mean single layer? If i wind my own i will have to rectify it with a bridge or just a diode?
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
Full-wave rectification is always good, but half-wave is fine if you are tight on budget. Check Steve Ward's CCPS page for details on what I'm talking about.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
Oil burner ignition transformers are usually 5-10mA, but that looks like it may be an electronic one, you probably are better off with the old iron transformer type. Is oil heating common in your area? If so you may be able to score a used transformer from a HVAC shop.
As for rectification, half wave is likely to give you problems with core saturation, you're really better off to spend a few bucks more on full wave.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
ok I will go with full wave rectification. So what about a dual stack flyback supply? I just want decent discharges nothing crazy, the thing is if i go with two fly backs how will i find voltage and current to calculate my tank cap?
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
If you drive it push-pull the voltage will be pretty close to the turns ratio, so you can drive it at a low voltage, maybe a volt or two and measure the output and extrapolate from there. Flybacks have limited current due to the very small wire in the secondary, maybe 1-2mA. Don't you normally pick a ballpark value for the cap and then tune the primary? The voltage can be adjusted by adjusting the DC input. It's surprisingly easy to wind your own ferrite HV transformer too, at the frequencies involved you can push 20-30V/turn from a modest size core.
Neon and oil burner transformers turn up on ebay from time to time for reasonable prices, and stopping at a sign shop if you can find one will likely net you a few. Flyback is a nice high tech approach but you shouldn't have to spend more than $10-$25 for either solution.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
For small tabletop coils, an small (say 7.5/20 or 9/30) NST is probably the best and most robust solution. If you want cute and tabletop, you can always go solid state - the unloaded fres of your secondary is around 1 Mhz, which is good for switching with MOSFETs.
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