PCB with integrated ribbon motor, transformer, pre-amp, XLR

[a soBer Newt]

@a soBer Newt, I played a little with FEMM last night. Cool stuff! Would you mind posting your source file(s) for the model you made? I'd really like to see the details. Thanks!

I do all my 3D modeling in Fusion360, Make a 2D drawing, Export that as a PDF into Illustrator to clean up any linework issues, and then export it as a DXF into FEMM. Their user interface make less sense then LTSpice.

mhelin That is one amazing paper​

 

[rubinstu]

@a soBer Newt, I ran the analysis on the FEM file, and also changed the steel loop to air, and indeed, I get the same results. Indeed, the loop makes a huge difference, from 0.093T to 0.38T.
It's unlikely that I'm going to be able to make or buy a suitable steel ring, but I was wondering if the same thing could be accomplished by using steel wire wrapped in a coil around the motor assembly. Instead of a rigid slap of metal, use the motor assembly itself as a bobbin and make a bunch of loops around it with steel wire.
Could this be modeled in FEMM?
By the way, my motor design originated from Fusion 360 as well, so I could probably export the DXF and see it for myself!
Thanks for the files and the tips.

 

[rubinstu]

Anyone have thoughts on using steel wired turns to capture the stray field?

 

[a soBer Newt]

Anyone have thoughts on using steel wired turns to capture the stray field?

Sorry been swamped at work. It probably would help not sure how much for sure. You might want to try some Perforated Steel sheets they could act like blast protection as well as some return path.

 

[rubinstu]

@a soBer Newt, it's funny. Using perforated sheets was actually my original plan. I was going to just encase mic's the wood box frame with it for hum shielding, but then I thought it might be more efficient and easier to just shield the transformers and/or the amp boards. At the time, I was not thinking about the efficiency of steering the stray fields. Also, McMaster-Carr is only about a 20 minute drive from my house (so same day / no shipping!). I think I may try the steel wires first and see if I can do an A/B comparison of the levels, etc. Thanks again for your input.

 

[ccaudle]

Anyone have thoughts on using steel wired turns to capture the stray field?

I think it should be like any inductor or transformer, any gaps between the magnet and the steel reduce the effectiveness, the gaps between the faces of the steel wire reduce the effective usable cross section for a given cross section filled with wire, so will take more total volume to have the same effectiveness as solid steel. So the tighter you can wind it the better.

 

[a soBer Newt]

@a soBer Newt, it's funny. Using perforated sheets was actually my original plan. I was going to just encase mic's the wood box frame with it for hum shielding, but then I thought it might be more efficient and easier to just shield the transformers and/or the amp boards. At the time, I was not thinking about the efficiency of steering the stray fields. Also, McMaster-Carr is only about a 20 minute drive from my house (so same day / no shipping!). I think I may try the steel wires first and see if I can do an A/B comparison of the levels, etc. Thanks again for your input.

I love going and picking things up from them at will call, are you by their Santa Fe Springs location?

 

[rubinstu]

I love going and picking things up from them at will call, are you by their Santa Fe Springs location?

Cleveland, OH area! I also love picking things up from will call. It's like getting a little glimpse into Willy Wonka's factory - except instead of Oompa Loompas and chocolate rivers, it's conveyor belts and Big Ass Fans.