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Registered Member #9252
Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253
A friend of mine was throwing his CRT (2006) I took it in and found the flyback inside was in relatively good condition. There were however a few odd things. Most of the flybacks i have seen / found had 3 red wires poking out of the flyback. Not this one. A thick black wire with the suction cup and a short white wire. After hooking it up to a 2n3055. It gave white hot arcs at 16 volts. I was impressed. But when i put a capacitor on the primary. I observed something. The white wire had a jet of corona spraying out. I put a light bulb on it and it turned into a plasma globe. I tried doing that with the Black wire and the Ground but none of them did it. So far it seems one output is DC and one is Ac... It begs to be submerged in oil as the pins make a mini-Lightning storm I will upload pictures sooner or later!
Edit: I used a capacitor on the primary to put the flyback into resonance. And suddenly i won't work again? With the capacitor attached i get the normal output without the capacitor. What happened? I tried replacing the capacitor , Rewiring the entire thing , And meter'd the capacitor. All of that did nothing. Any ideas?
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
idea; replace the 2N3055, preferably with a higher voltage transistor, igbt, or fet. Ensure adequate base/gate drive. quite likely your 2N3055 is injured.
Registered Member #9252
Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253
You know mosfets and igbts do not work in place of the 2n3055 I tried replacing the 2n3055 with another. But it was still out of resonance. I tried replacing the 2n3055 with a D2498 but still. No resonance . And is it it normal for a flyback to output booth ac and dc?
Registered Member #3943
Joined: Sun Jun 12 2011, 05:24PM
Location: The Shire, UK
Posts: 552
StormInABottle wrote ...
And is it it normal for a flyback to output booth ac and dc?
Could be the effects of capacitive coupling? Even at 20khz the capacitance of the internal diodes could be enough to pass enough AC current for a small corona discharge.
If you need still need a transistor for this circuit and you are in the UK then take a look in your local Maplins and see if the 2n3055 transistor they stock is like mine, ON branded and made in mexico.
I have yet to experience a failure, unlike the previous ST branded devices I was using. Even with 24v it doesn't seem to complain (my heatsink is too small for continuous operation at this voltage).
The gain is a bit on the low side but you can add a few more feedback turns and decrease the value of the lower resistor to something like 12 ohms, I got 3 inch arcs from one LOPT with this configuration.
Don't forget to add a reverse biased fast diode and small capacitor of around 22-220nF across the collector and emitter!
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
Could you post a picture or the part number of the fly-back in question (or even the CRT it was taken from)? I would love to do some background on it. It MAY contain a mini- circuit (hence only two leads + ground). I would also love to experiment w/ one and if they are common you may have found a unique part that lends itself to a variety of ideas!
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One flyback to rule them all?
