Date: Wed Feb 21 11:59:12 2007

Author: Bill Norwood

Subject: Re: Banana Plug Leads

Post:
Hi Dan,

Looks like good advice - I'll file it.

In case anyone still uses the 40-year-old Eico Battery-Eliminator Power
supplies, I will confess that I replaced the wiring on the variable
transformer swiper with this flexible test lead wire, because it must flex
so much.

Bill Norwood
Technician, Elementary Labs
Physics, U of MD

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Dan Beeker
Sent: Wednesday, February 21, 2007 11:46 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Banana Plug Leads

If you use small gage wire, breaking is a problem. I once made up a whole
bunch of alligator clip lads using standard 22 gauge stranded wire. Wires
started breaking from the first time the leads were used. I find the radio
shack alligator leads or those obtained in bulk from Digikey, Jameco etc.
generally work better although they also tend to break quicker than I would
like. It can be frustrating because students don't kow how to trouble shoot
things they can't see. (Often they don't know how to trouble shoot things
they can see but that's another discussion.) The real trick is to use "test
lead" wire because it has a lot of very fine conductors so they take bending
stress better. It is rare that the wires break. Belden 8899 works well. Its
description is Test Prod Wire, 18 AUG (85x#38) tinned cu, EPDM insulation.
The 85X38 I think means 85 strands of 38 gauge wire. There is also a smaller
gauge test lead wire, Belden no 8890 (miniature test lead wire) that is 24
gauge. I much prefer the larger test lead wire. Both are available from the
standard electronics suppliers.

Dan

Dan Beeker
Undergraduate Physics Lab Coordinator

Swain West 115
Physics Department, Indiana University
727 E. 3rd Street
Bloomington, IN 47405
Phone: (812) 855-5903
Fax (812) 855-5533
debeeker@indiana.edu

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Sam Sampere
Sent: Wednesday, February 21, 2007 10:49 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Banana Plug Leads


I used to do that. I replaced all the alligator clips on my Vernier probes
with those tips. I inserted another banana plug into the jack opening and
pushed the plastic cover on until it snapped.

These leads were problematic though. The wire near the plastic would break
inside the insulation. So, I went back to the as supplied alligators.

You are correct, they are made by Johnson. I got 'em through digikey.

Sam

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Dan Beeker
Sent: Wednesday, February 21, 2007 9:37 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Banana Plug Leads

Most of the department buys Pomona but make my own up. Our tips are
purchased through Newark though they can be had from other suppliers. They
are made by (E.F.?) Johnson. Colors are somewhat limited unless you by
thousands. Cable is standard test lead wire. The tips cost about $1.00 each
now so little money is saved but it is made up by the convenience of having
the length needed. It seems like I used to get a little metal block when I
ordered them but can't recall getting any recently. I do have several in my
tool box along with the "punch" if anyone needs one. Occasionally we have
faculty complain about how poorly they are assembled. But when I look at the
ones they complain about they usually have a patina that suggests they
predate the modern age. Assembled properly, the push on kind will work
practically forever. If you use a hammer and beat the plastic cover on they
will fail quickly. I have found using just enough pressure to seat the
plastic cover on the metal part ensures longevity. The long term failure
mode is generally the nylon cover ages, gets brittle and cracks causing the
cover to slip off the metal tip. I figure it takes between thirty and fifty
years for that to happen.

Dan Beeker
Undergraduate Physics Lab Coordinator

Swain West 115
Physics Department, Indiana University
727 E. 3rd Street
Bloomington, IN 47405
Phone: (812) 855-5903
Fax (812) 855-5533
debeeker@indiana.edu

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Jerry DiMarco
Sent: Tuesday, February 20, 2007 6:45 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Banana Plug Leads


There are replacement plugs for this type of cable. They have the

same look and don't need to be soldered. We did have to make a simple jig
(block with a hole in it) to assemble them. Got them from Newark, stock

no. 93F9164/...5 (red/blk)...


Jerry


At 11:54 AM 2/20/2007, you wrote:
>What I don't like about Pomona cables is that when an end breaks off
>(rare
>but it happens), it's very hard to fix, except by recycling like Santos

>does. I like the Pasco cables - they're a bit cheaper, the ends are
very
>easy to re-attach, and the durability is just fine. We get the kit of
>parts and solder the cables to our own lengths. It's a great project
for
>teaching my student assistants how to solder.
>-John


<><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

Jerry DiMarco
Manager of Lecture Demonstrations and Instructional Labs
Montana State Univ., Physics Dept.

Bozeman, MT

Our Motto: "What would your mother do?"








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