RIDICULOUSLY CHEAP PCB's!!

[Denots]

Received the test pcb coils this morning, they look ok.
I can put them on the CNC and cut the outer, not a problem but I'd prefer to have them done.

[ATTACH]47288[/ATTACH]


I'll take some measurements later but they are as ordered.
If they are Ok, I will keep the design on a square panel, add the circular Vslots and submit at various widths, add another board layout into the centre and let them do the panel etc.
Basically try different things. I have talked with them but they prefer the email trail which suits me too.

thats interesting so the pcb has the coil on it saving you from winding a coil? Will this perform just the same as a wire coil?

[Mdtoday]

thats interesting so the pcb has the coil on it saving you from winding a coil? Will this perform just the same as a wire coil?

Yes and no
It is another way to produce an inductance and for use with PI detectors, generally speaking, it comes with less efficiency than wound wire coils.
Higher resistance, cost, weight, inter-winding capacitance, size, have to be juggled to suit a practical design. Sometimes, they just won't be suitable.

[Denots]

Yes and no
It is another way to produce an inductance and for use with PI detectors, generally speaking, it comes with less efficiency than wound wire coils.
Higher resistance, cost, weight, inter-winding capacitance, size, have to be juggled to suit a practical design. Sometimes, they just won't be suitable.

I see that makes sense, I like the fact it’s nice and slim and you can practically bolt it straight to the bottom of the md, also I’d imagine it eliminates some of the false beeps when swinging from side to side?

[Mdtoday]

I see that makes sense, I like the fact it’s nice and slim and you can practically bolt it straight to the bottom of the md, also I’d imagine it eliminates some of the false beeps when swinging from side to side?

These pcb coils still require shielding and must be rigid enough that the board does not flex.
The false beeps, can be caused by earth field effect, or bumps to edge of coil, Faraday effect etc.
Same rules apply for pcb coils as to wire wound coils.

Cheers
Mdtoday

[Carl-NC]

Advantages of PCB coil:

• lower interwinding capacitance
• thin
• more rigid, less susceptibility to bump falsing (requires decent mounting)
• perfect repeatability

Disadvantages:

• higher series resistance
• more difficult to shield
• expensive
• wider profile
• lower magnetic field efficiency

Weight is likely a wash, but may depend on how shielding is done.

[green]

Advantages of PCB coil:

• lower interwinding capacitance
• thin
• more rigid, less susceptibility to bump falsing (requires decent mounting)
• perfect repeatability

Disadvantages:

• higher series resistance
• more difficult to shield
• expensive
• wider profile
• lower magnetic field efficiency

Weight is likely a wash, but may depend on how shielding is done.

A picture of two coils I posted awhile back. How much less than 9pf do you expect the PCB coil to be? Was expecting more of a difference in capacitance since the flat basket has more spacing. Almost no spacing with the flat spiral. Interested in how the PCB coil compares, inductance, capacitance and SRF.

[green]

Wondering if anyone has measured inductance and SRF of their PCB coils.

[Carl-NC]

Advantages of PCB coil:

• lower interwinding capacitance

Eh, not for now. I got my JLC-made PCBs a week ago or so, but been too busy to mess with them. Finally got them routed and tested. Results suck. SRF for the 10" coil is 604kHz, which is WORSE than a scramble-wound coil using magnet wire. My PVC-insulated winding is over twice the SRF, at 1220kHz.



I'm very certain the problem is the fact I used double-sided windings, and the ground terminal windings are directly under the peak signal windings. Either I need to stick with single-sided, or do a very complex layout to minimize top-bottom capacitance. For now, I will do nothing.

[green]

Eh, not for now. I got my JLC-made PCBs a week ago or so, but been too busy to mess with them. Finally got them routed and tested. Results suck. SRF for the 10" coil is 604kHz, which is WORSE than a scramble-wound coil using magnet wire. My PVC-insulated winding is over twice the SRF, at 1220kHz.

[ATTACH]47411[/ATTACH]

I'm very certain the problem is the fact I used double-sided windings, and the ground terminal windings are directly under the peak signal windings. Either I need to stick with single-sided, or do a very complex layout to minimize top-bottom capacitance. For now, I will do nothing.

Thanks

[Altra]

That's too bad. At least you were able to determine that approach is not the best. I wonder if you could stagger the top and bottom traces? So that the traces on one side are centered over the etched area of the opposite side? Thanks for posting

[Carl-NC]

That's too bad. At least you were able to determine that approach is not the best. I wonder if you could stagger the top and bottom traces? So that the traces on one side are centered over the etched area of the opposite side? Thanks for posting

I think that won't help much. What I'd like to do is one turn on top, then via to the bottom and do 2 turns, via back to top and 2 more turns, etc. The the high voltage is at the outside edge, and ground is on the inside edge. High V is never near ground.

EasyPC does spirals very easily, but arcs & semi-circles are difficult. Another day...

[nonkapo]

What about using ticker boards?