Flybacks always burn on my Driver... Why?

On a sunny day (Sun, 21 Jun 2015 19:59:06 -0700 (PDT)) it happened Luiz Paulo Damaceno wrote in :

Hi, very nice project. Is that a 555 timer in the generator? Maybe les distortio nwith a betetr driver / modulator?

I do not know the answer to your question but:

Color TV flybacks are probably not rated at more than 1.5 mA at 25 kV so say 37.5 Watt After that not only will any internal diodes short, but also the winding will overheat and burn.

Some are tuned to the third harmonc of 15625Hz, maybe Fred knows better? Fifth harmonic? Should be possible to check that with a signal generator.

Look up old postings where I measured this for a Helium neon laser supply.

Color monitor flybacks can be much higher frequency.

BW TV flybacks can only do a few uA before burning, say 500 uA.

When I was a kid I used an old car ignition coil to make HV :-)

You did wind your own? I see 'number of turns' 10 to 1500 very nice = 150 x flyback pulse, cool! Flyback could be 7 x 38 * sqrt(2) = 280

Color TV flybacks are probably not rated at more than 1.5 mA at 25 kV so say 37.5 Watt After that not only will any internal diodes short, but also the winding will overheat and burn.

Some are tuned to the third harmonc of 15625Hz, maybe Fred knows better? Fifth harmonic? Should be possible to check that with a signal generator. Look up old postings where I measured this for a Helium neon laser supply. You did wind your own? I see 'number of turns' 10 to 1500 very nice = 150 x flyback pulse, cool!

I always use 1 turn per volt as a rule.

Well, you do not need an arc. Point HV emitter, then modulating ring, and at a distance, the anode. Built sort-of like a tube, only no vacuum or filament.

Nice.

Anyway, a standard definition TV flyback actually resonates at about 70 KHz . I don't know how helpful that information may be because driving it at a higher frequency will get you less voltage, but it might be an option to be tter the fidelity. You will probabyl just have to pump it with more input v oltage.

Later TV designs actually capacitor couple dto the flyback, removing the DC and Enhancing longevity. For that of course you need a load choke.

In essence, by eliminating the speaker cone (or diaphagm as in electrostati c or planar) you are attempting to eliminate mass. I must assume the goal i s higher fidelity. therefore the best improvement should be made by upping the frequency to the point where it does not matter. Audiophiles have expre ssed a desire to take digital sampling frequencies up into the hundreds of megaheartz. you can't go there with old TV flybacks, but if yuo do, the tra nsformer is not likely to be all that big, except the secondary is gong to need some gnarly insulation. Actually THAT is what will account for the siz e, not the core and primary at least.

Are you using integrated flybacks ? I mean with the HV built in. Does that work, or are you scavenging for non-integrated flybacks ?

Tell you what, even though they are pretty much out of it, you might weant to try to contact Henri at Asti Magnetics. they probably have people around there who still know transformers and might have some nifty things up thei r sleeve. Actually I am not so sure they are evben there these days. Their cash cowws were flybacks for CRT TVs that are gone, and heads for VCRs that are gone. they also made a bunch of different HV components like focus spl itters and the like.

If you can get ahold of them people it might well be worth it.

With the HV RECTIFIER built in that is.

Oh, yes it is you said. But without some capacitance you are not getting DC, no would it really be desirable for this.

Getting an idea of what's actually going on might be a useful application of something like LTspice. Would require a few measurements of the transformers you're using, to get it into the ballpark of operation. Parallel resonance is hard on the switch - control of currents is more easily achieved with at least one series resonant element.

I wonder if you are sure of the actual source of audible effects is? It could just as likely to be the transformer core, or other mechanical apparatus/mounting hardware, as anything else.

RL

me problems...

ansformers (in tv operates in 15khz aprox), but here I need more...

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o the flyback is from a CRT monitor (but haven't a capacitor) and in the se cond video is from a 29" TV... Both flybacks have an internal diode... I th ink I need a AC flyback... Or no?

You have no means of preventing a residual DC current through the pri-Mary. Mary then blows the driver.