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Registered Member #1498
Joined: Thu May 22 2008, 07:08AM
Location: Hong Kong
Posts: 72
I've got this FBT recently but I wanna know the pin configuration of it. Can anyone give me the data sheet of it?I'm sorry that the labels on it are not clear enough but I'll upload more image of ti later. Another qeustion: What's the use of the two wires above the pins and that of the two buttons on the FBT?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
The two wires are focus and screen.
You can find the HV return pin by connecting the negative of your >20V supply to the HV output and the positive to one lead of a voltmeter, while probing the pins on the base with your other probe. The one which gives highest voltage reading is the HV return.
You don't need to know the other pins as you'll wind your primary on the exposed core anyway.
BTW this transformer has a built-in HV capacitor so it is not suitable for drawing arcs.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
lhl_henrylui wrote ...
What's the use of the two wires above the pins?
Dr. Kilovolt wrote ...
The two wires are focus and screen.
They provide focus and screen voltages to the CRT tube.
Edit: BTW means "by the way". When there is a capacitor on the output of the transformer, you won't get hot arcs but just loud individual sparks which can't be drawn.
Registered Member #1643
Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039
How high do you think the HV capacitor is Dr. Kilovolt? Most likely too slow to be part of a teslacoil capacitor id guess (if you wanted to bother with boiling the core and removing it all...That's too bad that he ended up finding one that has a built-in capacitor to kill all the fun of arcing :(
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Well, sometimes the cap has a separate ground connection in which case it can be left floating, but as you start outputting a few tens of kV it will most likely spark over.
You can still use it for Tesla coil if you put a high voltage resistor in series with the output which limits the discharge current to a few Amps.
There is also a possibility to draw arcs from it if you put a suitable high voltage inductor in series with the output (this can be a flyback-secondary-like coil on a ferrite core, maybe even a ferrite rod is enough).
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Don wrote ...
How can you tell if the FBT has a built in HV capacitor?
You power it up and if it is a loud white spark it is a capacitor XD.
If the flyback looks like it has a kind of square or rectangle place on it, that is likely the HV capacitor. I have taken a sledge hammer to a dead flyback which had a capacitor, and it was indeed just a type of film. It was pretty large, actually. About half as big as the whole flyback. Considering the capacitor had to be made to withstand a constant 25-30kv, i would have to say it was a few nf, like 1-5 or so.
Just a guess, that was only judging by the physical dimensions.
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Unknown flyback transformer
