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Registered Member #1764
Joined: Thu Oct 16 2008, 03:52AM
Location:
Posts: 10
Well i think i have looked at almost every howto online but have not goten far. I built a 3055 circuit and it works, but the output it only like 2-4kv (or 1-2 centimeter) I have tried it with 2 9v batteries (just to get a feel for it before i move up) but also tried a big 14v transformer with 5 amps. But still not much. this is the flyback, i know it is small so i dont expect much but i expect more. The only think i am doing different is im useing a 5 watt 270 ohm resister and a 33ohm 1 watt resister instead of what it calles for (could not fine the exact resisters at frys)
So if someone could help me out. If i need to get a biger flyback i may be able to find one somewhere.
Registered Member #1107
Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792
That looks like a mini flyback from a portable b/w tv. Those are not going to give out much power so i would suggest you looking for a bigger one. They can be found in regular computer monitors and tv's the people throw out and they are amazingly easy to obtain. About the resistors i dont think they have to be crucial seeing the driver is self resonant but as long as they are generally close they would work fine. One thing that you should try is to increase or decrease the number of primary turns until you get the maximum amount of output voltage. Good luck and play safe.
Registered Member #51
Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263
That flyback is fine if you want DC. Any 9v battery combo will never work well at all. The 2n3055 driver is really bad. The ZVS driver is very impressive and only uses a few more parts. Your primary and feedback winding are far too small. because you're not worried about turn density, you are perfectly fine in using normal wire for the primary. Anything is better than the windings you have now. Find an old computer power supply and use the wire from it if you can. Computer PSU's are also great to power things, as they give 12v at several (tens) of amps and are easily put in series (after secondary side isolation).
Also, someone will likely be displeased with you for posting a 1024 pixel wide image.
Registered Member #1764
Joined: Thu Oct 16 2008, 03:52AM
Location:
Posts: 10
cjk2 wrote ...
That flyback is fine if you want DC. Any 9v battery combo will never work well at all. The 2n3055 driver is really bad. The ZVS driver is very impressive and only uses a few more parts. Your primary and feedback winding are far too small. because you're not worried about turn density, you are perfectly fine in using normal wire for the primary. Anything is better than the windings you have now. Find an old computer power supply and use the wire from it if you can. Computer PSU's are also great to power things, as they give 12v at several (tens) of amps and are easily put in series (after secondary side isolation).
Also, someone will likely be displeased with you for posting a 1024 pixel wide image.
Ok, fixed :)
I do know that the battery and the 3055 is bad but this for now is more of proof of concept for me. But looking on youtube and what not they seem to be getting much better voltages.
Also just to make sure i read it correct, you are saying i need thicker wire for my primary correct? But the feedback looks fine?
And last, if i were to use a higher amp power supply, would that have any risk towards the 3055? i dont have a heat sync for it yet (only doing this in 20 sec max useage so i dont burn it out) but would a 10 amp or so ps burn it out instantly?
Registered Member #540
Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969
The reason the feed back is fine and you need a larger pri is because the pri will be carrying most of the current to the flyback. You won't burn out the 3055 (actually they can sometimes burn out but not due to heat related issues) if you increase the power supply current. The circuit will draw the same amount of current no matter how much the power supply can put out (the max current for the power supply has to be more than the driver can draw). Right?
Registered Member #1764
Joined: Thu Oct 16 2008, 03:52AM
Location:
Posts: 10
Myke wrote ...
The reason the feed back is fine and you need a larger pri is because the pri will be carrying most of the current to the flyback. You won't burn out the 3055 (actually they can sometimes burn out but not due to heat related issues) if you increase the power supply current. The circuit will draw the same amount of current no matter how much the power supply can put out (the max current for the power supply has to be more than the driver can draw). Right?
Yeah, i will mess around with it.
thanks a lot everyone. i bet i will be back in a day or two with more questions :P
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
The internal primary is bad because there is higher coupling and less leakage inductance, this means it will draw huge currents from your driver when you short it. It is much better to wind the primary opposite the secondary on the core, as this will result in "natural" current limiting, not saying the internal primary may burn out and ruin your transformer, while you can just rewind the external one...
Registered Member #1749
Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497
OK that explanes why my vector inverter works so well drawing more current is what the circuit is for it can handle more than a 2n3055 sorry.brianmay27 And i wish i could donate a fly back to u haha.
Registered Member #1764
Joined: Thu Oct 16 2008, 03:52AM
Location:
Posts: 10
Thanks.
But i should be able to fine one. there is a store called weird stuff. i bought the one i have now for $3 (they had a full box of new ones) so i bet i could estly find one there.
And just before i go kill my self, I did take apart a old computer PS and make it into a +12, 0, -12 and +5 volt multi box. I put a 10 amp fuese on it to make sure it would not short, but i just want to make sure that i will not blow anything out (the primary [which i will add a better gauge wire on it], the 3055 or the resisters).
And that brings up a different question, would i want 5 volts or 12 volts or what thanks again
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Need help with flyback transformer.
