Acquiring Custom Magnetics

[Mastrofski]

I've been toying with the idea of developing a Flyback SMPS, however a big part of the design is getting the transformer properties to behave right. I was wondering if any of you guys had any experience with ordering custom magnetics. I'm assuming there would be an upfront engineering cost, and then a flat rate for the parts afterwards. I don't mind paying a little more for the engineering costs if they're an active partner and catch some of the mistakes I'm bound to make, but I would like the costs to be reasonable, I know I've heard of custom toroids being $150 for development costs and $4 a piece after that, which seems fair. The problem is I don't know which companies I should be looking into and which I should be avoiding.

[AndyC_772]

I've done this.

I was fortunate, in that I was able to find a local company with both design and manufacturing capability. Crucially, their design engineer was experienced enough to know what I actually needed in terms of the design of the magnetics, given the information I was able to provide about the design into which it would be going.

He was also diplomatic enough to help me understand and rectify my mistakes... a skill also not to be underestimated!

I think your estimated development cost is out by about an order of magnitude, but otherwise you're not far off.

Are you sure you need a custom transformer? I know Wurth do some flybacks with lots of separate windings that can be connected however you choose... might be worth a look if the voltages and power levels you're looking for are compatible?

[T3sl4co1l]

FYI, I know of Xfmrs and Coilcraft on the national level, and a few other places locally.

Coil winders are common enough to find regionally, within a state or a few, but probably not, like, around every large city.  So there's a lot to choose from.

If you have a design in mind, we can talk about it here, too, or once you get a proposal we can check it.

Tim

[Mastrofski]

I've done this.

I was fortunate, in that I was able to find a local company with both design and manufacturing capability. Crucially, their design engineer was experienced enough to know what I actually needed in terms of the design of the magnetics, given the information I was able to provide about the design into which it would be going.

He was also diplomatic enough to help me understand and rectify my mistakes... a skill also not to be underestimated!

I think your estimated development cost is out by about an order of magnitude, but otherwise you're not far off.

Are you sure you need a custom transformer? I know Wurth do some flybacks with lots of separate windings that can be connected however you choose... might be worth a look if the voltages and power levels you're looking for are compatible?

If you don't mind me asking, what ballpark was the development cost? Some fellow students of mine needed some custom toroids for their senior design project and I'm going off of what they told me, so maybe they got an educational discount of sorts. I've looked into Wurth a little bit, but perhaps I'll check them out further once I'm closer to actually designing that stage.

FYI, I know of Xfmrs and Coilcraft on the national level, and a few other places locally.

Coil winders are common enough to find regionally, within a state or a few, but probably not, like, around every large city.  So there's a lot to choose from.

If you have a design in mind, we can talk about it here, too, or once you get a proposal we can check it.

Tim

Thank you for the heads up of those companies, I'll definitely look into them down the road. I'm actually in the process of designing a Bench power supply and I'd like to feed the circuit directly off of mains, but thus far I've been able to get away with buying a premade unit that gives me some supply rails. I figure the SMPS design will be fairly thorny so I'm putting that off until I have all my ducks in a row. It's good to know that there are resources here to help me out with the design when I get to that point.

[Monadnock]

I find that places like Xfmrs or Coilcraft or Renco won't even talk to you unless your design will have volume production orders behind it.

Might be easier to design around a core that is available through Digikey and buy a small quantity of wire and tape off of ebay and wind it yourself. This is what I do for small runs.

[Alex Eisenhut]

http://www.amidoncorp.com/

[Siwastaja]

+1 for learn to do it yourself. It's not difficult at all. All the difficulty goes in design and calculations, and having someone to physically build it for you doesn't automatically solve this problem at all, unless you buy design as a service, too.

Also, because the design on paper may be a tad difficult, parasitics and imperfections playing a role (also the fact that you usually don't know exactly what you want from the transformer because it depends on the rest of the circuit), it's usually easiest to actually prototype and measure; hence, you need to be able to make different test transformers, change the windings, etc., and you don't want to wait and pay every time.

So, just learn how to do it. Building prototype magnetics is super fun, IMO.

When you have your design ready to be produced in maybe hundreds, then you can ask for quotes. Protos and a few dozen test production units - do it yourself.