Author Topic: How to buy a flyback transformer? (Read 10122 times)

king.oslo · « **on:** March 11, 2013, 03:47:41 pm »

Hello there,

Mouser and DigiKey dont have flyback transformer categories. Seems they have massive mains frequency transformers though. Say I want to transform for 15V to ~120V 1A, how do I find one on, say Mouser?

Thank you for your time.

Kind regards,
Marius

NiHaoMike · « **Reply #1 on:** March 11, 2013, 04:02:54 pm »

You'll most likely have to buy the parts and wind your own. Or as it turns out, your requirements are similar enough to the ones inside power inverters so you could just buy a cheap power inverter and modify it.

king.oslo · « **Reply #2 on:** March 11, 2013, 04:07:41 pm »

Thanks for that. Is there a website or resource or tutorial which will tell me which calculations I need to make, and also what parts to buy?

Thanks.

Kind regards,
Marius

Marco · « **Reply #3 on:** March 11, 2013, 04:22:56 pm »

Flyback transformers for xenon flash capacitor chargers are widely available ... the secondary insulation will be a little over-engineered for your purposes, but the current capacity and turns ratio are in the right area.

http://www.coilcraft.com/da2032.cfm (you can buy directly from them)

There are other manufacturers of these kinds of transformers too but coilcraft has the easiest to search website ... finding stuff like the current capacity for say the transformers from Wurth is a pain.

PS. PCB/circuit design for switching power supplies is non trivial.

king.oslo · « **Reply #4 on:** March 11, 2013, 05:43:18 pm »

Hello there,

N1 and N2 are suggested primary and secondary turns, right?

That looks like quite a nice tool!M

king.oslo · « **Reply #5 on:** March 11, 2013, 05:57:43 pm »

What is the norm in choice of wire?

Thanks.M

kxenos · « **Reply #6 on:** March 11, 2013, 06:29:35 pm »

On the second picture, on the right it gives you the cable data you need. But I think that because using 4mm^2 wire will be rather impractical, you can use 6 turns of 2 wires of 2,5mm^2 in parallel.

king.oslo · « **Reply #7 on:** March 11, 2013, 08:42:55 pm »

CMA as in crystal methamphetamine? I suspect it is not

What does the CMA abbrevation stand for in your post?

Thanks.

Kind regards,
Marius

NiHaoMike · « **Reply #8 on:** March 11, 2013, 09:00:23 pm »

Some laptop power supplies are about that power level and are usually flyback topology.

But for your use, it seems like the cheapest way is to modify a power inverter.

king.oslo · « **Reply #9 on:** March 15, 2013, 09:59:00 pm »

Hello there,

Ive bought some cores.

I started by winding primary 3 windings and secondary 30 windings. I am feeding in 12V_RMS @ 8A square wave on the primary side.

I am only getting about 3 volts induced on the secondary. I was expecting closer to 100V.

Are you able to recommend steps I can take to troubleshoot my tansformer?

Thanks.M

notsob · « **Reply #10 on:** March 15, 2013, 10:15:51 pm »

A picture of what you have made would be helpful

king.oslo · « **Reply #11 on:** March 15, 2013, 10:17:08 pm »

Sure, I can wind a new one tomorrow and post a picture.

Thanks.M

Neilm · « **Reply #12 on:** March 16, 2013, 11:31:39 am »

Check the primary current waveform. It should be a nice ramp up to max current. If it isn't you are probably overloading the core.

Neil

AndyC_772 · « **Reply #13 on:** March 16, 2013, 11:39:50 am »

Depending on your requirements, you could do worse than one of these:

http://katalog.we-online.de/en/pbs/search/Power_Magnetics/Flexible_Uebertrager

They're a range of flyback transformers with many windings all broken out to separate pins, so you can customise the turns ratio by connecting them in different configurations. No need for any winding yourself.

king.oslo · « **Reply #14 on:** March 20, 2013, 12:43:26 pm »

Probably doing something wrong.

I just wound the primary, and the secondary straight on top of that, held down with capton tape.

Attached is a picture of something which is not working very well. Can you spot the problems?

Thanks.M

NiHaoMike · « **Reply #15 on:** March 20, 2013, 01:25:40 pm »

You need the other half of the core and the wires are too thin for any real amount of power.

king.oslo · « **Reply #16 on:** March 20, 2013, 03:10:58 pm »

What do you mean by "the other half of the core"?

I am sure the secondary wire is too thin for my desired current, however, the problem is that this tranformer is only capable of inducing a few volts on the secondary. I could be switching 100V on the primary, and only see 3 volts on the secondary.

Kind regards,
Marius

king.oslo · « **Reply #17 on:** March 20, 2013, 05:37:22 pm »

Sure, but why is my setup inducing no voltage in the secound half? I have the correct turns ratio, so it should have induced a much higher voltage. Correct?

Thanks.M

Sedengr · « **Reply #18 on:** March 20, 2013, 06:59:13 pm »

If you do not test with the other half of the core you have an open magnetic circuit which is easily saturated. The power you are inputting is being lost in the core without any linking into the secondary.

If the test you did was with what was in the picture, try the test with the other half of the core in place to provide the field path.

king.oslo · « **Reply #19 on:** March 20, 2013, 07:11:43 pm »

Thanks!M


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Author Topic: How to buy a flyback transformer? (Read 10122 times)

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