Recent content by rickford

Ok, that makes sense. Well, thank you all that contributed. I'm about ready to commit to a layout so I guess here goes...

What is waste stream volume?

I have done some more experimenting with resonance and a function generator. This is what I have so far... The PCB coil: Tuned resonant frequency with .15uF cap in parallel, 31kHz. Calculated inductance based on resonance and known capacitor in parallel, 176uH. Q of tank circuit, about .55...

Note on the pdf that the 4 inner layers are used for the coil. There is no copper on the top and bottom layers except for the via's and the connection pads. This is done this way to protect the coil in case it momentarily rubs while spinning during setup.

Try this...http://files.engineering.com/getfile.aspx?folder=bf413f23-0dfd-46fc-8973-29b6fcd3fc82&file=CoilBoard.pdf

Well, I guess that didn't work. Looking for another way...

This is about the best I can do with the program I have. See attached pdf file.

If this is true, then you may have hit on the problem... though I have trouble seeing why it would be true. The layout is this... looking down on the board, a imagine a connection point at 12:00 position. The connection point is 2 terminals. From the right connection, a trace travels upward...

Yes, the current should be running in the same direction, as the loops all go around the circle in the same direction. I don't have an inductance meter, but I did put each into a tank circuit and using a function generator and a scope, I measured the resonance frequency and solved for the...

I have a hard time getting my head around the minute details of this. If the field doesn't pass through the copper, then how does the copper know it's there? Magnetics was not my strongest class back in school. It's as if the wire has an invisible lever arm sticking out and the magnetic flux...

I found a calculation of AC resistance due to skin effect, and it was minimal, assuming I did it right. Only a couple ohms.

Interesting that you suggest staggering the coils like that. That's exactly what I don't have. Right now, all 4 layers lay right on top of one another so that you can see right through the gaps. What happens to the magnetic flux as it passes through one of the copper layers? Is it...

BTW, the relative permeability of FR4 is 1, so I think this supports the idea that FR4 is not creating any more losses than the air wound coil.

No, I didn't think there would be any losses there. It doesn't seem to be magnetic in any way, and it's not conductive, so I don't have to worry about eddy current losses.

I have a small circuit that runs on the secondary coil. It rectifies the power from the coil and filters it to get a clean DC power supply. The power supply working range is anywhere from 6.5V to 25V. With the hand wound coil, I can tune the power circuit up to provide as much as 25VDC (at...