PSN-L Email List Message

Subject: Re: Magnet Wire
From: "steve hammond" shammon1@.............
Date: Sat, 15 Jan 2000 09:42:25 -0800

I like the counter idea and will try it.

I do have a question.  I was wondering if anybody had the wire constant i=
for enamel insulation #52 wire. My little Electronic Pocket Handbook stop=
at #44.

 I really enjoyed reading the information that Sean-Thomas presented abou=
coil making and was wondering if he could explain what Johnson noise due =
resistance is and how to measure it.

 I have been making scramble wound coils using #52 wire mainly because Pe=
Rowe came to a PSN meeting in 93' and gave me some large bobbins of the
stuff. I played with this wire for awhile and after breaking enough of it=
clutter up the floor in my garage, figured out a method to get it onto a
coil form. I used the white 2-inch plastic spools from RadioShack 22-gaug=
wire. First sand the frame so that the wire won't snag on an edge when be=
wound. I use a small Drumel lathe with a wall light dimmer controlling th=
speed. Hang the wire above the frame so it can fall off the bobbin. Cut a
hole on the inside of the white frame and feed the wire through the hole.
Tape the wire down on the outside for winding. Pull some extra wire down
from the bobbin, hold your breath, start the Drumel lathe, feed with one
hand and pull wire down with the other. Breath when you think you have it
under control or are going to pass out. In about five minuets, you'll hav=
e a

I have made several coils this way. They all have been in the 17K range.
Even without electronics, they will drive a galvanometer on a drum record=
I unwind a little wire when I want to match two coils for a pair of
seismographs. I like to use a cow magnet inside the center hole of the
plastic frame (1/2-dim - length 2.5-inch) and just mount the magnet to th=
boom of the Lehman. If you do mount the magnet on the boom, make sure the=
is no steel in the floor or seismograph enclosure walls that will draw th=
boom to the steel. To make the connecting wires portion, wrap a few inche=
of wire around a 6-inch piece of 22 gauge wire and then solder them
together. Epoxy the connector wire to side of the frame. Then wrap the
complete coil assembly in black electrical tape to protect it when it's
being installed or when your working around the seismograph. I've got two=
use today that have lasted 8 years. My 2C worth.

Steve Hammond   PSN Aptos, California

-----Original Message-----
From: barry lotz 
To: PSN-L Mailing List 
Date: Friday, January 14, 2000 7:16 PM
Subject: Re: Magnet Wire

2=A2 :    Regarding counting turns, I have a Radio Shack digital counter.=
has a 4 digit LCD display with reset etc. It counts contact between two
pins. I set ,securely, the counter on the bench. I attached one pin,thru =
wire to my vice. I secured the other pin via a wire to a wiper on the dri=
chuck. The drill was held horizontally in the vice with the spool in the
chuck. Each revolution of the chuck contacted the two wires an counted a
revolution. I ran several hundred turns when I constructed my LVDTS. I
haven't used the counter with the Lehman though. I just recorded the
overall DC resistance of the completed coil. I agree with Karl. Finer wir=
will result in a larger output. 36-40+ ga is good. I have tried to wind 4=
gage and found it very frustrating. I breaks easily and hard to solder wh=
broke. Patience is a good tool also. Keep the faith :)

Paul Jebb wrote:

> Gentlemen:
> Regarding  a Lehman seismometer:
> Is 30 gauge copper wire satisfactory for the coil, if so, how much
> should I use.  I plan to put the wire on with a drill, but counting the
> number doesn't seem possible.  The original design called for 400 ohms
> of resistance.  Can anyone speak to this issue?
> Yours truly,
> Paul Jebb


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Larry Cochrane <cochrane@..............>