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Registered Member #180
Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187
I think you should put a strike ring or something on there, it looked like there were alot of primary strikes. Even if it didn't die from the strikes I don't think they can be good.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Steve Ward wrote ...
I doubt its a problem of burden resistance, ive made all sorts of CTs with resistance of less than an ohm, to 10 ohms with no real difference in performance. You must be careful to avoid additional "loops" in your wiring though, as this would impact the signal from the CT output.
If you arent generating long sparks, then this steady-state kind of primary current is typical. I only see the primary current drop down significantly when making long sparks. Also, the multiple notches at the start suggest your primary is tuned too high for best performance, and you may be running too many RF cycles.
So in short id tune it up and then turn it up .
Yeah, 10 ohms is still rather low V/turn so I wouldn't normally be concerned for a 1/1000 stack.
Steve, good call, I am a dipstick, In all my frantic tweaking of the coil. I changed my primary and didn't measure it. The primary originally was running at 185KHz and secondary was at 190. The new primary (copper tube) with a bigger cap only ran at 200KHz which is way above the secodnary Fo. I was slowly pulling windings off my secondary to try and tune it since I was maxed out on the primary. The secondary looked kinda dumb anyway being a little too long. Well anyway I never finished the tuning because my IGBT's blew, again and im all out now. Here's a video I made of it during some of this process.
Your primary characteristic impedance is decent 10 ohms, and with that kind of spark you must have tuned severely low if your current is indeed peaking at 800A.
To increase certainty of current measurement, I'd probably use something like 1:100CT on a single core with low value (1 ohm or so) burden resistor. You only need a volt or so on the burden for measurement with scope.
Banned on 3/17/2009. Registered Member #487
Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617
I will probably try that Marko but I did test the CT on another coil and the waveform looked normal. I'd actually rather wind 100 turns on a single core anyway.
Eventually when i'm done screwing with it, I'll add a strike ring. It does seem really desperate to commit suicide by primary strike though.
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Odd looking primary current waveform
.