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Biduleohm
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MessageSujet: Re: Electronics    Sam 12 Nov - 20:39

I know what is a flyback, I just ask for the model Smile

A tv flyback, ok Smile

In theory any voltage between 10 and 200V it's depend on the primary winding Wink

The original primary use 150 to 180V but for DIY we re-wound a primary for use it with 12 to 30V generally Very Happy

Th DC is easier because a 555 + a mosfet suffice. Moreover, with a push-pull design (just one more mosfet) you feed the FB with AC from DC psu Smile

AC isn't a good solution, the FB need a square signal à high frequency, not a sinus at 60 Hz...
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MessageSujet: Re: Electronics    Sam 12 Nov - 21:01

ive seen them with no flyback and just adding a winding and running it to a transistor this way when the pulse starts it sends a signal to the transistor to tern off then the field collapses and it starts agen and repeats. this generates about 200 hz

Ive head trouble with fets Mad
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MessageSujet: Re: Electronics    Sam 12 Nov - 21:03

why not just run them on 100+ v dc then?? Twisted Evil i will start work on my driver soon as i get some parts in the mail
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MessageSujet: Re: Electronics    Sam 12 Nov - 21:12

You can run it on pulsed DC (but not on pure DC) at 100V if you want, like I've already said the primary winding is designed for 150 to 180V generally Wink

It's more simple to use 12V à 5A than use 100V at 0.5A for the driver so we often use 12 or 24V but if you want you can use 100 or 200V without any problem Smile
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MessageSujet: Re: Electronics    Sam 12 Nov - 21:33

well i just got some transistors rated for 100v at 25 amps MMuahaha Twisted Evil

i will pulse it with a 555 but i need to find a schismatic to control hz. i will test around with it but the only tuning spot i found are the capacitor (going to be .1 uf) and the capacitor discharge pin 4 and 6 i think
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Biduleohm
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MessageSujet: Re: Electronics    Sam 12 Nov - 22:05

No, the capacitor stay at the same value, the resistors varies Smile for example: http://www.capturedlightning.org/hot-streamer/kv2/kv2/hv/555_fbt/index.htm Wink

Type 555 flyback driver on google and enjoy Smile
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MessageSujet: Re: Electronics    Sam 12 Nov - 22:40

the capacitor plays a big role if you have a 1 uF cap ut might be going about 3 hz if you have a .1uf it can be going 200 khz

^ that was gathered info from my experimenting with it Smile
but if you change the resister out with a potentiometer 0- 50k you can generate 200 m hz as i did Twisted Evil

now i have to figure out what frequency would best drive a flyback from 100 hz to 200 m hz Rolling Eyes

what would you guess? i want to make it so i can both drive a flyback and since its a 555 i want to play audio over it too.. 200khz i think works for music but what best drives a flyback
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MessageSujet: Re: Electronics    Sam 12 Nov - 23:10

Yes, but you calculate the value of capactitor with the value of potentiometers in median position for the needed frequency. Like that the frequency is about that you want and can be adjusted precisly with potentiometers (one for frequency and one for duty-cycle) Wink

The up limit of 555 is few MHz if I'm right Smile

The tv flyback are designed for a particular frequency (wich is about 15.5 kHz) wich is the resonnant frequency of the FB. If you turn away from this frequency the efficiency go down...

It can be possible to use a odd harmonic like 3*15.5 or 5*15.5 for better sampling if the application is audio modulation (for plasma speaker I imagine, right ?) but i've never tried...

If it's for a plasma speaker the 555 ins't recommended, it's not designed for audio modulation. There are some specialized IC for that, you can find schematics and part name on google with jey-words plasma speaker schematic (and theirs synonymes) Wink
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MessageSujet: Re: Electronics    Sam 12 Nov - 23:40

how do you change duty cycle?

the 555ic will work for audio modulation about 70 k Hz will modulate music threw an arc fairly well. Smile it might not be the best but it will work for me since i am giving it 2 jobs

i want to be able to drive a fb as well as possible and on a different setting play music Smile

i believe i will need a double throw switch changing resister values one around 16 KHz and one around 70 KHz both will use the same potentiometer that ranges from 0-50 k ohms giving me a wide sweeping range..

then i will need to find a suitable power supply Rolling Eyes i would like 40v at 5 amps then i need to smooth it alot and crate a large capacitance so it will not interfere with the 555 and be able to maintain a large arc Smile
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MessageSujet: Re: Electronics    Dim 13 Nov - 0:07

charge time = (Ra + Rb) * C
and discharge time = Rb * C
(or the reverse)

So Ra change duty cycle and Rb change frequency (and duty cycle) Wink with 2 diodes (1N4148) you can separate totally the frequency and duty-cycle change Smile

You can also use a separate psu for 555 but one psu with correct decoupling on 555 there is no problem Smile
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MessageSujet: Re: Electronics    Dim 13 Nov - 0:13

found it! i had to change the value of the cap slightly and now i can run from 2.5 KHz to 207.2 KHz with one set up this should give me a grate tuning ability Smile
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MessageSujet: Re: Electronics    Dim 13 Nov - 0:20

my duty cycle is around 52% until it gets to 100 KHz after that point the duty increases proportionally. at 209 KHz the duty is 86%

i do not know how accurate this is my much meter might not be rated for reading duty at such high Hz
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MessageSujet: Re: Electronics    Dim 27 Nov - 5:56

i completed the driver for the fly back and im getting about 10kv but im only using a 2 amp supply so i think i will go and get a 40v 11amp transformer supply Twisted Evil

and the resident frequency with what i was using was about 33k Hz good thing i made it adjustable Smile
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MessageSujet: Re: Electronics    Dim 27 Nov - 14:41

Ok Wink
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