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Registered Member #3926
Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525
I've tried a couple of different transistors, the transistor is getting warm, and the resistors is getting warm, but no flyback output :/
I've also tried that schematic thanks. The transistors and resistors were getting warm on the schematic you posted.
I've tried another transistor, first seeing if it switches a 12v bulb, it did, but it was dim, I then hooked it up to the flyback and I had a camera flash tube on the flyback outputs to see it easier there was a small spark then nothing, the transistor it's extremely hot, and I now think it's broken.
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
There is no problem because of the maximum voltage of the transistor. The problem is that high-voltage transistors may also have low current gain (HFE), and this may impede the oscillation. Anyway, if anything gets too hot to be touched something is seriously wrong.
Registered Member #3926
Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525
Well the transistor was too hot to touch, very painful is you would keep your finger there.
But I'm going to open an old TV in a bit, see what I get.
Anyway I've got a 85W TV here and I was wondering shall I run the flyback with the TV intact, or take the flyback transistor out with the rest of the goodies?
I just read that you can make a oscilloscope out of a TV? Hmm this current TV I have is quite new although there another 80's TV in my attic, could I make one with the new TV? Do they actually work good?
Registered Member #3926
Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525
Antonio wrote ...
There is no problem because of the maximum voltage of the transistor. The problem is that high-voltage transistors may also have low current gain (HFE), and this may impede the oscillation. Anyway, if anything gets too hot to be touched something is seriously wrong.
I just got another transistor from a TV, and again it is making 12v bulb glow dim, and there is a few milivolts on the flyback output, I'm using the transistor from the TV 33ohm and my 270ohm resistor. everything's OK, so how can I resolve this problem?
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
It's making the bulb glow dim with what connection? Never connect a multimeter to the HV output. If the device happens to work the multimeter will be immediately destroyed. If it works you will see clearly visible sparks to the ground pin of the flyback. This transistor is a Darlington pair, two transistors, and needs a higher base-emitter voltage to turn on. You may have to increase the value of the 27-ohm resistor to make it work.
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