PCB electromagnet?

I had an idea the other day to take a copper clad circuit board, and etch some sort of spiral into it to make an electromagnet. I'm not sure if this would have any particular advantages over some wire wound magnet, but the idea is just very intriguing to me.
It seems like having the coil so flat and right there at the surface would make it very strong when flush with some ferrous object. What do y'all think?

I don't know a lot about the differences to having the coil flat like that and made out of PCB tracks (even if I could hypotheticaly find a formula to describe it in my old physics books ), and presumably it'd be less effective without the benefit of a proper core, but I'm fairly sure I've seen such an approach used in some windmill generators on some webpage somewhere?

Not sure I can find it right now, but it was pretty interesting. IIRC they had like a ring of several (8? 12?) such coils around the board, with the rotor going across them as it spun.

Look at these links. The transformers do not have wire. The windings are made from copper clad circuit boards. I have used the Pulse Engineering parts.

https://www.electro-tech-online.com/custompdfs/2007/09/plandesi.pdf
**broken link removed**
http://www.planars.com/index.html

ronsimpson said:

Look at these links. The transformers do not have wire. The windings are made from copper clad circuit boards. I have used the Pulse Engineering parts.

https://www.electro-tech-online.com/custompdfs/2007/09/plandesi-1.pdf
**broken link removed**
http://www.planars.com/index.html

Click to expand...

That's pretty cool, I hadn't even considered using that concept with transformers. It looks like they are able to make some high powered stuff incredibly compact this way.
I'm not too good with electromagnetic theory and such, do you know why they require such high frequencies? I guess I couldn't use something like this on 60Hz 120Vac? Does pulse engineering sell in small quantities or would I have to order in some massive bulk amount to get some.

I wonder why these things are not more prevalent?

Why high frequencies?
Electricity is like water.
If you needed to carry water from the well to the house and you had a 5 gallon can you could only walk 3mph. If you could run 100mph then a small cup could move more water.
Did that answer why small high frequency components?

One of my profs passed around a wafer from such a transformer in class once. It was from (I believe) a "portable" x-ray machine used in airports. It was a large square board with a hole in the middle (presumably for a core). The transformer was made from many of these boards stacked on top of eachother. I think the board may also have been many layers thick.

Power transfer is significantly higher at higher frequencies. That's why they're not used for 60hz AC. I didn't see any kind of core material used, then again I didn't look real close at them but if there's no core material then it could be used at very high frequencies increasing efficiency. The advantage of doing this on a PCB is that in bulk it's cheaper than winding a coil, and since their flat they lend to stacking well.

Printed Circuit Board Coils like this are Already being used on MANY METAL DETECTORS.
This isn't anything new.
The Main advantage is a Low Internal Capacitance.
The main disadvantage is a somewhat high DC resistance.

Peepsalot said:

I had an idea the other day to take a copper clad circuit board, and etch some sort of spiral into it to make an electromagnet. I'm not sure if this would have any particular advantages over some wire wound magnet, but the idea is just very intriguing to me.
It seems like having the coil so flat and right there at the surface would make it very strong when flush with some ferrous object. What do y'all think?

Click to expand...

PCB inductors are generally used at higher frequencies.

Another disadvantage is that I imagine that a lot of the flux is radiated which is useful in a metal detector but a pain in an oscillator or filteras it lowers the Q.

I've never seen a PCB coil used as an electromagnet though, I can't see how it would be any better than a proper electro magnet.