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Registered Member #567
Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147
And it's a SSTC. That's because I don't like the concept of the SGTCs.
Well finally. After about a year of waiting, my examinations are finally over and I get to start work...
I've finished soldering the driver board, with the interrupter. That's the GDT at the side, which, I have to say was a pain to wind. The cable is so stiff... I used the entire Cat-5 cable so that I can parallel the wires for more current; I don't trust that thin cable. The Cat-5 cable and twisted cables go to a four way switch and two variable resistors, for the interrupter, and that big yellow thing is the dc blocking capacitor.
Here's a mockup of the half bridge, leaning against the heatsink. (The reflection of the flash... Ouch.) I was lucky enough to find a terminal strip which fits the MOSFETs exactly. As in, the legs slot in nicely!
I'm just waiting for the wire for the secondary and the driver chips to arrive now.
Banned on 3/17/2009. Registered Member #487
Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617
LOL, yeah I can see why that was a pain to wind. Probably overkill for thsoe FET's. I only use part of the cat 5 cable. I wind one two pairs twisted lightly together then I parallel the white striped ones. Works perfect. About 15 turns.
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
You don't have to worry about current problems in the CAT5 cable; it is much more likely to die of overvoltage-related arc-overs and shorts. Not yours specifically, just any GDT in general.
Registered Member #567
Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147
Really, that wire looks awfully thin, though. I have succeeded in melting some wire insulation off in my PSU before, and those wires were much thicker. Admittedly I was running at about 5A, but meh...
Registered Member #567
Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147
Uh oh, here's a problme. My order for the TC4420s has been delayed until January 08! I don't suppose anyone can think of another supplier other than RS? I live in Singapore, so quite a few suppliers are alredy out.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Using gross number of turns like that on your GDT will only make things worse due to lots of additional leakage inductance.
For core of that size you aren't going to need but few turns.
Calculate after thedatastream's site and don't use more than + a turn or so. James actually already gave a good margin.
Wire thickness is nothing to worry about. You anyway put a resistor like 2 orders of magnitude bigger than the resistance of the wire in series.. We use CAT 5 just because of insulation and handyness. Better than it would be to use shielded cable with shield as a primary... but CAT5 is good enough for most things.
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Another first tesla coil...
