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Adam Munich

Thu Nov 04 2010, 11:14PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Ahh don't count your chickens before they hatch, find a FBT first. There are plenty of 555 based drivers and you'll need to get different parts for each one.

Amplifiers have plenty of resistors, capacitors, and transistors. They also have nice heat sinks.

Michalis.Biochem

Thu Nov 04 2010, 11:18PM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
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Posts: 69

Ok! I ll see what i can find and i ll inform you ASAP.

Michalis.Biochem

Fri Nov 05 2010, 02:22PM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
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Posts: 69

I came in contact with the local tv's repair shop and i am expecting to get lots of FBTs, so i guess some of them will be the open type ones.
So i have began gathering parts for the ZVS. Unfortunately, i can't seem to find a place where they sell the ultra fast diodes. Ebay might then be the solution here.
I've found these ones but i don't know if they are ok.

Michalis.Biochem

Fri Nov 05 2010, 04:36PM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
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Posts: 69

Finally, i have found a FTB!
I can't find any specifications about it so i have posted 2 photos.
I can only find that it is from muRata and it has MHF042-02 as a serial number. Unfortunately i can't find any info about on Google or the muRata website.

Adam Munich

Fri Nov 05 2010, 07:36PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

That looks like a decent FBT. Unfortunately it's quite hard to find data on those things, but to find HV ground all you need to do is arc to the pins on the bottom. The pin that gives the fattest arcs is ground. The other pins are various voltage supplies for other circuitry on the TV board, and two will be the internal primary. The red wire is HV out, and the white wire is a very low current HV output for the focus. Not much can be done with it. Also, don't rely on the wire's insulation to protect you. Tape the wire to a drinking straw or something like that if you want to manipulate it.

The UF4007 is a perfect diode for a ZVS, 75nanoseconds is more than enough speed.
This thread gives some good info on ZVS designs.

Michalis.Biochem

Sat Nov 06 2010, 09:31AM

Registered Member #3340 Joined: Wed Oct 20 2010, 07:28PM
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Posts: 69

So basically now, i have to build the ZVS with the specifications you gave me and then connect it to the FBT(i don't know how, i am a bit confused about schematics). Give the whole circuit some power and see where the fattest arc are. Correct me if i am wrong anywhere.
And what about the HV ground? Do i have to connect it with the actual ground?( i know, i am a bit noob with these things)

Adam Munich

Sat Nov 06 2010, 03:37PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

There are two ways to make a ZVS. One requires only one power supply. The problem with it is that it sometimes falls into a parasitic oscillation at higher voltages where it will start to "scream". Then things get all screwy. I built this version, but mine never falls into oscillations unless there is no air gap in the FBT. Even a paper thin gap stops it from wigging out.

This one requires a separate 12V source. It eliminates the oscillation problem at higher voltages, but it may still freak out without an air gap. I'm not too sure about that.

Since you will be likely running this thing at 12V either one will work, and they'll both give hot fat arcs. Here's a video of mine going at different voltages. At the end I was getting 1.28 kW out of the FBT at 36V in.

The inductor can vary which is why it says 47-200uH. Lower inductance = more current, higher = more voltage. Just adjust it to your liking. I would also keep the HV ground separate from the power supply. There's no need to connect it to the circuit and risk something going awry burning things out.

Just in case you don't know what an air gap is, look at the ferrite core of the flyback. In the center there will be a gap with a spacer in it. They do this to break the magnetic field lines, because a FBT needs to not only step up the voltage, but store energy for a certain amount of time.

Tesla Fan

Sat Nov 13 2010, 08:47AM

Registered Member #3353 Joined: Sat Oct 23 2010, 11:21PM
Location: Greece
Posts: 90

Hm, ZVS, Flybacks and batteries...

Have you seen this:

- PICTURES DELETED -
Candy box HV 40 kV AC

From "our own"

Tesladownunder
?

Also, since this thread started as "CCFL", i have two power supplies from some small PC case CCFL (12V DC input), i could definitely spare one of them if you think you can make something out of it. I do not know anything about the output of these power supplies, but they both have a 3KV cap at the end of the circuit. My opinion is there are no good for anything bigger than a 2cm high secondary (if that). Pics to come soon...

- PICTURES DELETED -

PS. Can i send pictures with a PM? If anyone knows please give me a heads up...

Pinky's Brain

Sat Nov 13 2010, 04:45PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

CCCFL transformers don't necessarily have the insulation necessary for truly high voltages, they are only designed for a couple thousand Volt. Trigger transformers and CRT flybacks are designed for 10s of kV.

CCFL power supplys do seem to make nice regulated low current intermediate voltage power supplies though (for charging a small Marx or something).

Tesla Fan

Sat Nov 13 2010, 07:03PM

Registered Member #3353 Joined: Sat Oct 23 2010, 11:21PM
Location: Greece
Posts: 90

I have never tried to build anything with these, just have them in my junk box

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