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Flyback driver...need help

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Gavin

Wed Nov 21 2007, 08:22PM

Registered Member #478 Joined: Tue Jun 20 2006, 11:57PM
Location: Shrivenham, United Kingdom
Posts: 8

Sorry for looking an idiot, but what does ZVS stand for? Also why is it that the circuits to drive LOPTs/fly-back transformers are so simple, yet to drive one externally you need to use so much more electronics; is that you are pushing them to their limit?

Cheers

Gavin

Wed Nov 21 2007, 08:24PM

Registered Member #478 Joined: Tue Jun 20 2006, 11:57PM
Location: Shrivenham, United Kingdom
Posts: 8

I meant the circuits used in TVs to drive LOPTs are simple, yet the circuits described here are more sophisticated.

Dr. Dark Current

Wed Nov 21 2007, 08:43PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Gavin wrote ...

I meant the circuits used in TVs to drive LOPTs are simple, yet the circuits described here are more sophisticated.

Simple? eh.. Have you ever examined the driver in a TV? Just the base drive for the HOT uses a lot of components- transistors, inductors, even a transformer. There are maybe hundred components in the whole horizontal power section. It is anything but simple.

"Our" drivers are super-simple compared to what you can find in a regular TV.

ZVS is zero voltage switching, and here it refers to the dual MOSFET resonant flyback driver, see

xandros01

Thu Nov 22 2007, 03:08AM

Registered Member #1128 Joined: Mon Nov 19 2007, 09:50AM
Location:
Posts: 3

Hi again guys!...The monday i start making the single transistor driver from the powerlabs page because i wanted to start with simplest circuit, and i want that you tell me if iÂ´m going for the right way. Here are some photos of my unfinished work:

One question:

Shoul i use the internal primary or wound my own in the exposed ferrite core?

xandros01

Thu Nov 22 2007, 07:39AM

Registered Member #1128 Joined: Mon Nov 19 2007, 09:50AM
Location:
Posts: 3

Weeeee!!!! Yeah baby!!! It works!!! this is so beautiful, the flyback gives like 2 or 3cm long of arc. IÂ´m almost crying of the emotion

. Thanks to all of you guys for help me here. I used the internal primary and wound my own feedback of about 2 turns and iÂ´m so glad to say that it finally works!!!

Kizmo

Thu Nov 22 2007, 07:42AM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

Thats great!

Now you should take a look for ZVS driver :)

You will be surprised how big arcs flybacks can do

Gavin

Thu Nov 22 2007, 11:49AM

Registered Member #478 Joined: Tue Jun 20 2006, 11:57PM
Location: Shrivenham, United Kingdom
Posts: 8

jmartis wrote ...

Simple? eh.. Have you ever examined the driver in a TV? Just the base drive for the HOT uses a lot of components- transistors, inductors, even a transformer. There are maybe hundred components in the whole horizontal power section. It is anything but simple.

"Our" drivers are super-simple compared to what you can find in a regular TV.

OK, the circuits are complicated, I looked at a couple of TV circuit diagrams and I stand corrected on the complexity. However, although there is some feedback circuitry, the final driving stage is a single transistor, heatsinked but small. I guess I am wondering if the load presented by a TV tube is lower than what HV experimenters try to apply to these fly-back transformers, and if they are designed for TV tube loading, how long do fly-backs last when driven by ZVS circuits.

All that aside: With ZVS does the parallel motor cap ensure the current and voltage are in phase, so that the switching semiconductor disipates less power?

Cheers.

Dr. Dark Current

Thu Nov 22 2007, 03:51PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

xandros01 wrote ...

Weeeee!!!! Yeah baby!!! It works!!! this is so beautiful, the flyback gives like 2 or 3cm long of arc. IÂ´m almost crying of the emotion

. Thanks to all of you guys for help me here. I used the internal primary and wound my own feedback of about 2 turns and iÂ´m so glad to say that it finally works!!!

I remember that feeling

as my first flyback gave 5mm purple arc

Nobody cared it was drawing 80 watts and the transistor was smoking hot in seconds, the little purple screaming arc was just amazing.
Now I can make 30cm flaming arcs from 4-flyback but for some reason it doesn't impress me as much as the first purple arc did.

Mates

Thu Nov 22 2007, 04:23PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

jmartis wrote ...

Now I can make 30cm flame-like arcs from 4-flyback

You mean you pull 30cm plasma... That's something else than 30cm arcing (no fly-back can stand such voltage). I achieved 15cm arcing from one big-screen TV flyback but I killed it soon. The coumputer monitors fly-backs can stand like 10cm arcing but that's the top limit. (BTW: the distances are related to simple 1mm wires as HV electrodes)

Bauerb2

Thu Nov 22 2007, 04:41PM

Registered Member #973 Joined: Tue Aug 28 2007, 07:32PM
Location: Pittsburgh, PA
Posts: 66

i remember when i got my first flyback to work. i jumped around in joy because it took me forever to get it right, but it was awesome.

i have been plannign on building a zvs driver, because i have seen the success people have had with it. what i have built now is a halfbridge 555 driven one i use to drive a small 6-7" tall tesla coil.

check it here---->

good job xandros, keep it going.

-Andrew

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