Author Topic: How to convert DC to AC (for a flyback driver)  (Read 2184 times)

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Offline pranav.appu.472

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How to convert DC to AC (for a flyback driver)
« on: April 25, 2017, 12:12:30 pm »
I have a 12 V 8AH big battery and self made voltage amplifier. All I now need is a SIMPLE way to make the battery output AC with enough hertz to activate the flyback transformer. Please help I'm on the last step to complete it.

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Offline Molenaar

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Re: How to convert DC to AC (for a flyback driver)
« Reply #1 on: April 25, 2017, 12:52:30 pm »
Look up the Mazilli driver, that should do quite well.
 

Offline Seekonk

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Re: How to convert DC to AC (for a flyback driver)
« Reply #2 on: April 25, 2017, 03:25:41 pm »
That transformer will produce DC with its internal diode.
 

Offline Zero999

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Re: How to convert DC to AC (for a flyback driver)
« Reply #3 on: April 25, 2017, 08:56:32 pm »
The simplest way I know of.

http://madlabs.info/flyback.shtml
 

Online james_s

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Re: How to convert DC to AC (for a flyback driver)
« Reply #4 on: April 26, 2017, 12:49:45 am »
These are some others, I've built the mk II one and it works nicely.

http://uzzors2k.4hv.org/index.php?page=flybacktransformerdrivers
 

Offline pranav.appu.472

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Re: How to convert DC to AC (for a flyback driver)
« Reply #5 on: April 26, 2017, 12:55:41 pm »
Thanks. I've made a single transistor driver with 2N3055 but the spikes killed by 2N3055

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Online T3sl4co1l

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Re: How to convert DC to AC (for a flyback driver)
« Reply #6 on: April 26, 2017, 12:59:32 pm »
Thanks. I've made a single transistor driver with 2N3055 but the spikes killed by 2N3055

That's what the circuit is designed to do, by the looks of it.

Tim
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Offline Zero999

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Re: How to convert DC to AC (for a flyback driver)
« Reply #7 on: April 26, 2017, 01:00:32 pm »
Thanks. I've made a single transistor driver with 2N3055 but the spikes killed by 2N3055
Well the circuit I posted above doesn't use the 2N3055 but the NTE284, which has a much higher voltage rating then the crappy old 2N3055. Failing that, try adding a snubber network.
 

Online T3sl4co1l

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Re: How to convert DC to AC (for a flyback driver)
« Reply #8 on: April 26, 2017, 02:46:34 pm »
This is a bit more responsible of a design,



And yes, for once I'm claiming a 555 is useful for something. ;D

+V can be whatever.  For instance, you can use about +100V and use the primary winding inside the FBT itself (trace the PCB to find these pins).  For the external winding (usually 3-10 turns), 12-24V will be suitable.

An RCD peak clamp snubber, across the transistor, might also be a good idea, to prevent overvoltage.  The RC damper helps, but doesn't limit the peak very much.

I don't have a complete schematic handy, but you would add a diode, resistor and capacitor, connected to the transistor collector/drain just as Q3, D1, C2, RL are connected here: https://www.seventransistorlabs.com/Images/AltiumDiscreteFlybackSch.png
Typical values would be D1 = UF4007, C2 = 10nF and rated at least 2 x +V, RL = 10k 5W or thereabouts (depending on +V, turns, operating frequency, power level, etc.).  You want RL to be small enough that the clamping voltage (the DC voltage on C2) isn't obscene.

Tim
Seven Transistor Labs, LLC
Electronic design, from concept to prototype.
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