The reference thread for newbies!

[EtLa]

This is one of the most confusing thread of my forum reader career


As I wrote somewhere in this thread, my counter has no battery.
It's a mechanical stroke counter.

I think that DrStrangelove is talking about your ohmeter battery.
On the photo you joined it doesn't look like you have 7500 turns on a 9mm (0.354") tall bobbin.

[Steve Conner]

It really does sound like you got the wrong gauge of wire. Maybe it's 42SWG, which works out around 38AWG.

[Biarnel]

It's not easy to know it for certain, anyway.
Is there a way to have certain proof of the wire gauge? A caliper it's not accurate enough..

[EtLa]

hmmm 7500 turns with 38AWG magnet wire would end up with a huge coil. Are you shure that your counter at hight speed doesn't count twice one turn?

[DrStrangelove]

Give that man a drink!

It really does sound like you got the wrong gauge of wire. Maybe it's 42SWG, which works out around 38AWG.

Outstanding insight, Mr. Conner.

42SWG ~ 38AWG. When I run the simulation with 38AWG,
7500 winds at 62% fill factor (scatterwind) is 1800 ohms,
much as Biarnel initially reported.

-drh

[Biarnel]

What's that simulation software?
Where may I find it?

[EtLa]

here

With Zielgler Pick-up calculator http://pickups.myonlinesite.com/programs.php I get 3642 ohms for 7500 turns

[Dave Kerr]

Well, if Steve gets a free drink, I'm a bit thirsty myself

[EtLa]

7500 winds on that coil

[DrStrangelove]

Dimensions dementia

First off, Dave Kerr gets kudos and a glass of his favorite beverage
for suggesting that the wire might NOT be #42 AWG.


There was some confusion about the bobbin core size initially, too.

Using Adam Zeigler's pickup winding calculator at
http://pickups.myonlinesite.com/pickup.php
select millimeter, and plug in these values:

Core Length: 28
Core Width: 10
Core Height: 9
Bobin Width: 40
Bobin Thickness: 3

Wire Diam: .1016
Insulation Diam: .1143

...then recalculate for 7500 winds, get 1590 ohms, about 10% low.
This value corresponds to an ~88% fill factor which derives from an
assumption of hexagonal lattice packing.

I get ~1800 ohms at 78% fill factor, so I'm guessing Biarnel tends to
wind more tightly with #38 (.1016mm) than when using #42 AWG (.07mm).

Empirically, scatterwinds average about 62% fill factor.

My winding estimater program is still a prototype in C that will probably
get translated into JavaScript too late to be of any use.

-drh

[Biarnel]

First off, Dave Kerr gets kudos and a glass of his favorite beverage
for suggesting that the wire might NOT be #42 AWG.

Ok, I have a micrometer now.

I'm reading in INCHES and WITH the insulation.
Please tell me if I should burn off insulation before taking any measurement.

The wire I used reads 0.0028" WITH INSULATION.
The guy who sold it keeps on saying that it's an AWG42 and that I'm not tensioning it enough.

UPDATE!
Burning away insulation, I read 0.0022", wich is AWG42 accordingly to various tables.

[EtLa]

Ok, I have a micrometer now.

I'm reading in INCHES and WITH the insulation.
Please tell me if I should burn off insulation before taking any measurement.

The wire I used reads 0.0028" WITH INSULATION.
The guy who sold it keeps on saying that it's an AWG42 and that I'm not tensioning it enough.

by looking at the coil I estimate around ~3800 turns with 42 AWG
Core Length: 28
Core Width: 10
Core Height: 9

[Biarnel]

by looking at the coil I estimate around ~3800 turns with 42 AWG

PLease believe me: it's 7500 turns.
Coil size tends to alter perception, but it's quite a fat and bulky winding.
keep in mind that mags are 10mm dia.

Could the tensioning be the key?

[EtLa]

with 7500 tuns I estimate at least ~4mm of winds.

[Biarnel]

I get ~1800 ohms at 78% fill factor, so I'm guessing Biarnel tends to
wind more tightly with #38 (.1016mm) than when using #42 AWG (.07mm).

Sorry, but maybe my knowledge of english language is betraying me.

What do you mean with that?
I did not use #38, that was a #42, I just checked with a micrometer (0.0025" without insulation).
Are you trying to tell me that my tensioning is poor? I just make the wire slide thru my index and thumb...