A new chat has been created:

My beloved 545B has had the fading trace problem for years. Keeping the humidity low in the lab has worked for a while, but now it's driving me nuts. Love to know if I could get it rewound and for how much?

By: Conrad Hoffman <choffman@...>

View/Join This Chat

Do not reply to this message to post to the chat. You can participate in chats only through the group's website.

Hi,

My transformer winding machine lurks quietly to my left as I sit
at my computer workstation composing this post....

I think it is time that I re-explain my transformer project, and
provide a little insite into its status:

Just prior to starting the winding project, I was at a lull in my
career, with plenty of free time and a desire to do something
worthwhile.

A couple of seemingly unrelated happenings occurred:
One, I needed a couple of carts for my 7000 series scopes, and two,
my son, caught the math and physics bug at school.

The carts happened to come with a couple of very nice looking
scopes, so I was now the owner of a 545B and a 547... each with a
bad case of the previously unknown to me HV transformer disease.

The project started as a way of scratching my own itches, as they
say.

Wanting to nourish my high school son's new found interest in math
and physics, I decided that it would be a good idea to involve him
in a fun project that would hopefully stoke his interest while subtly
giving some grounding for his future endeavors.

I started working on making a Farnsworth Fusor.

In spite of having a background in laboratory procedures, and
already owning all of the necessary vacuum equipment, vessels, etc ...
I was stuck on the HV power source necessary to propel the deuterium
nuclei into their fusion state.

The usual Spellman HV power supplies were hard to come by, and way
too expensive for frugal old me, so I decided I would have to make
my own.

The diversion into making replacement transformers for Tek scopes was
my way of learning how to make the fusor's transformer, and getting
my scopes fixed...

In the end, time slipped by, and I never made the fusor, but my son
earned his Phd in nuclear physics, and a few hundred transformers got
wound for you folks on tekscopes and tekscopes2.

I wound several hundred transformers, all manually, for the "princely"
sum of $100 each.

The problem is, when I add up all of the "overhead" involved in the
winding, and divide it into the return, I was working at a deep loss.
Not a very hopeful business model...

I was, I think my wife lovingly coined the phrase, "Wasting my time!"

When I look at all of the side effects of the project, there was much
value, beyond the monetary returns.

1) I, and a few of you, got scopes fixed.
2) My son got his first real work experience.
3) He studied at Carnegie-Mellon, and WUSTL, graduating with
honors.
4) He got his Phd in theoretical physics.
5) And I sorta think the work we did on high vacuum, HV transformers,
and winding machines had a little something to do with
his first internship at Los Alamos National Labs, and later
internship at General Dynamics...

So yes, it was definitely worth doing.

But, in the course of making transformers expectations were created,
and promises were made, and the internet is eternal, so even long
after I am gone, folks are going to still hope that I will wind for
them...

So how to move forward?

The engineer in me felt it was important to make the winding
process more reliably, with considerably less tedium than the
current method, so I created an new automated machine, with none
of the twiddly, adjustments of the old. The computer took the
place of all of the cams, rubber wheels, and gears I previously
used.

The machine was successful in improving winding accuracy, and
removing most of the tedium, but automation created problems of
its own, owing to the use of stepper motors to handle the motion
required in winding coils...

Prior to retirement, I had an urge to get my projects in order,
and to do as many of the hundreds that had piled up as possible.
Because age was sneaking up on me, I gave higher priority to those
that were becoming harder and harder for me to do...

Now that I am fully retired, so is my wife, so my needs are her
needs, and her needs are my needs, and winding is still low priority.

I work on the machine a little from time-to-time, but it is not
going as fast as I hoped. I am trying out a roller stylus mechanism
that another fellow rediscovered, and I have high hopes for it.

So, that is where things stand. Hope for a long gloomy winter,
as I get more indoor work done when I am not outside cutting and
splitting firewood.

-Chuck Harris

On Mon, 12 Feb 2024 10:42:33 -0800 "Group Notification"
<[email protected]> wrote:

A new chat has been created:

My beloved 545B has had the fading trace problem for years. Keeping
the humidity low in the lab has worked for a while, but now it's
driving me nuts. Love to know if I could get it rewound and for how
much?

*By:* Conrad Hoffman <choffman@...>

View/Join This Chat ( /g/TekScopes2/chat/12174 )

Do not reply to this message to post to the chat. You can participate
in chats only through the group's website.

Chuck, if you ever start back up in the rewinding business I’d like to send you the transformer from my 565 that needs some help. Please keep me in mind. I’d pay more than $100 for it as well.?

Sorry about the chat thing. I wanted to send a PM but couldn't figure out how to do it; hey, I'm getting old! Anyway, great to read about your adventures and I fully understand that we have priorities, not to mention the physical abilities to get things done. Now, I have a lot of enameled wire, a homebrew winder (just a drill chuck, crank and turns counter) and, I think, even the Tek transformer drawing. I've wound transformers for switching supplies and other stuff, but the physical details of the Tek transformer are a bit beyond me. I'd give winding one a try, but I don't want to wind it ten times to get it right! Would you be willing to share any helpful hints if I wanted to give it a go? I love my 545B (both of them) but in all honesty I'm wondering if it's time to dump them and get a cheap Siglent digital to pair with my 7000 mainframe. Of course I couldn't bear to scrap them, I can no longer lift them and finding anybody local that would actually use them, as opposed to just grabbing the tubes, is probably a pipe dream.

When I did the original winding, I told all on this group. You might
try looking for my original postings.

The transformer is really best wound using a "universal" wind, which
is a self supporting style of winding that keeps the potential between
every wire that comes near to other wires fairly low. This also keeps
the capacitance coupling between the windings low allowing for a higher
Q.

A factor that confuses many is that all windings are bifilar, tapped
when necessary, except the last several hundred turns. One of the
bifilar wires is used to feed the cathode circuits, and the other feeds
the grid circuits. That makes the difference in voltage between the
two wires in the bifilar pair only about 70V. If you segregate the
various winding sections into layers of their own, you end up with
very high voltages between the sections, and could have a flash over.

However, you can wind bifilar, in layers, using the "flyback" method,
where every layer of wire gets covered with a layer of tape, then
flys back over the wires in the layer to the starting side, and
gets another layer of tape before the next layer begins. This keeps
the layers isolated so the couple hundred volts they generate, at
1.6V/T won't arc over the winding.

Vacuum potting in beeswax after you are all done is helpful, but not
100% necessary with the "flyback" technique.

-Chuck Harris


On Thu, 15 Feb 2024 13:33:15 -0800 "Conrad Hoffman"
<choffman@...> wrote:

Sorry about the chat thing. I wanted to send a PM but couldn't figure
out how to do it; hey, I'm getting old! Anyway, great to read about
your adventures and I fully understand that we have priorities, not
to mention the physical abilities to get things done. Now, I have a
lot of enameled wire, a homebrew winder (just a drill chuck, crank
and turns counter) and, I think, even the Tek transformer drawing.
I've wound transformers for switching supplies and other stuff, but
the physical details of the Tek transformer are a bit beyond me. I'd
give winding one a try, but I don't want to wind it ten times to get
it right! Would you be willing to share any helpful hints if I wanted
to give it a go? I love my 545B (both of them) but in all honesty I'm
wondering if it's time to dump them and get a cheap Siglent digital
to pair with my 7000 mainframe. Of course I couldn't bear to scrap
them, I can no longer lift them and finding anybody local that would
actually use them, as opposed to just grabbing the tubes, is probably
a pipe dream.

开云体育

Thanks! I'll see how much history I can find. Not sure about my patience and other virtues, but I do have an excess of dogged perseverance once I get started on something. ?

On Wed, Feb 14, 2024 at 08:38 AM, Jean L. RUELLE wrote:

pure Bonheur

Pre happiness

larry

I now now more French!

A few things I can supply to encourage you to find your
"quiet virtues" as described by Dave, are:

1) use double stick cellophane tape for your inter-winding
insulation. The Scotch archival sort meant for sticking
photographs into an album is ideal. The electrical
insulation needs are minimal, and the tape will hold the
next layer firmly in place, preventing unwinding if you
relax the wire tension.

2) You can easily break up this job into a bunch of 5 minute
segments. Keep a tablet of paper next to your simple winder
to keep track of what turn you are on, and other details.

3) make your taps by dragging a loop of wire off to the
desired side, and twist it into a becoming the termination
lead. I use a pointed hook with a handle to make the
twisting easy.
4) use one of the tnermaleze types of wire. That way all you
need to do to tin the wire is put a blob of solder on your
soldering iron tip, and run it over the twisted up wire.
5) remember that solder dissolves copper and incorporates it
in the alloy. Keep your soldering time on these fine wires
short.

You can make a simple winder by cutting out two pieces of
soft pine, or plywood into rectangles about 1.5x 3 inches in
size.

Drill through both pieces simultaneously near the top with
a 1/8 inch bit, and hot glue the two rectangles spaced about
an inch apart onto another board, with the drill bit in
the holes to maintain alignment.

When the glue is set, remove the drill bit, and replace it
with a bent up piece of wire that has been formed into a small
crank. Coat hanger wire will do nicely.

Insert the wire into the two holes. You might want to put a
couple of nuts, beads, or a standoff between the handle and
the board to keep the wire handle from rubbing...

On the end of the wire that sticks out past the two rectangular
pieces of wood, carefully wind up adhesive tape to make a
mandrel to support your coil former. Use a couple three toothpicks
as wedges to keep the former on the "mandrel", and you are
ready to wind.

-Chuck Harris


On Fri, 16 Feb 2024 16:54:04 -0800 "Conrad Hoffman"
<choffman@...> wrote:

Thanks! I'll see how much history I can find. Not sure about my
patience and other virtues, but I do have an excess of dogged
perseverance once I get started on something. ?

开云体育

On Sat, Feb 17, 2024 at 08:35 AM, Dave Wise wrote:

double-stick tape

Where 'double-stick' = double-sided: referring to tape with adhesive on both sides
Then, you can get double-sided polyamide tape. (not saying you need that... and not saying you don't want that.)
The adhesive is either silicone based, or acrylic based... where acrylic adhesive is water based (mostly) and silicone adhesive is not water based (mostly).?
I suppose if you want to avoid acrylic... then you'd want an 'acid free' or 'neutral cure' silicone.?

I've used 1 mill PFT='polyamide film tape' ... which about 1/4 the diameter of 38 gauge wire. (check that) There is also the thickness of the adhesive to take into account.
Kapton tape is PFT; but according, at least, to Dupont: Kapton is PFT; but, not all PFTs is Kapton?
There is at least some variation in high temperature performance? 300 F to 400 F for many PFTs... whilst Kapton can do 300 C to 400 C

Anyway... on Amazon... generic PFT is about 10X as expensive (sans shipping) as from China (free shipping to here)... and the Amazon stuff is probably from China anyway.
You can get (probably good quality?) PFTs on Mouser or Digikey;but IME, they are usually single sided, for use in wave soldering.

Hi David,

My real winder was much more than that, and my computerized winder
even further.

However, if you are going to wind only one transformer, having to
turn a crank 733 times, over several days, really isn't that big of
a deal... the big issue is keeping count of the turns.

-Chuck Harris




On Sat, 17 Feb 2024 16:35:56 +0000 "Dave Wise" <d44617665@...>
wrote:

I'm saving your post in my notes. I agree with everything.

Great idea on the double-stick tape. I wish I'd thought of that.
I also ran a bead of Corona Dope at the edge of the tape before each
layer to ensure that wire didn't sneak down past the tape.

After reading your winder description I have to revise mine from "low
tech" to "moderate tech". I included a powered tensioner, using a DC
motor from a ruined belt drive phonograph. Rubber band as belt.
Soup can as pulley. Scotchbrite pad for friction. I still found
myself humming the Flintstones' theme as I wound.

I also fashioned a turns counter, from a microswitch and a frequency
counter in events mode. Yes I had to filter it... I used a sewing
needle stuck into a dowel as my nozzle. Before starting, I covered
some dental floss in valve grinding compound and ran it through the
eye to polish it a bit.

Dave
________________________________
From: [email protected] <[email protected]> on behalf of Chuck
Harris <cfharris@...> Sent: Saturday, February 17, 2024 6:51 AM
To: [email protected] <[email protected]>
Subject: Re: [TekScopes2] New Chat: Is Chuck Harris still winding
545B transformers? #chat-notice

A few things I can supply to encourage you to find your
"quiet virtues" as described by Dave, are:

1) use double stick cellophane tape for your inter-winding
insulation. The Scotch archival sort meant for sticking
photographs into an album is ideal. The electrical
insulation needs are minimal, and the tape will hold the
next layer firmly in place, preventing unwinding if you
relax the wire tension.

2) You can easily break up this job into a bunch of 5 minute
segments. Keep a tablet of paper next to your simple winder
to keep track of what turn you are on, and other details.

3) make your taps by dragging a loop of wire off to the
desired side, and twist it into a becoming the termination
lead. I use a pointed hook with a handle to make the
twisting easy.
4) use one of the tnermaleze types of wire. That way all you
need to do to tin the wire is put a blob of solder on your
soldering iron tip, and run it over the twisted up wire.
5) remember that solder dissolves copper and incorporates it
in the alloy. Keep your soldering time on these fine wires
short.

You can make a simple winder by cutting out two pieces of
soft pine, or plywood into rectangles about 1.5x 3 inches in
size.

Drill through both pieces simultaneously near the top with
a 1/8 inch bit, and hot glue the two rectangles spaced about
an inch apart onto another board, with the drill bit in
the holes to maintain alignment.

When the glue is set, remove the drill bit, and replace it
with a bent up piece of wire that has been formed into a small
crank. Coat hanger wire will do nicely.

Insert the wire into the two holes. You might want to put a
couple of nuts, beads, or a standoff between the handle and
the board to keep the wire handle from rubbing...

On the end of the wire that sticks out past the two rectangular
pieces of wood, carefully wind up adhesive tape to make a
mandrel to support your coil former. Use a couple three toothpicks
as wedges to keep the former on the "mandrel", and you are
ready to wind.

-Chuck Harris


On Fri, 16 Feb 2024 16:54:04 -0800 "Conrad Hoffman"
<choffman@...> wrote:

Thanks! I'll see how much history I can find. Not sure about my
patience and other virtues, but I do have an excess of dogged
perseverance once I get started on something. ?

Hi Roy,

Don't over think this!

I used Scotch Permanent Double Sided Tape that came
in 1/2" x 250" disposable hand held dispenser thingies,
and is marked as "Photo Safe".

It is double sided tape, meant for sticking a photograph
into a scrap book, or album. It is acid free, and has
stickum that dissolves in alcohol or naptha, but not water.

It is very similar to the old Scotch cellophane tape,
only with a layer of stickum on each side. It comes
in the same sort of one time use tear off containers.

They say it is an "acrylate" adhesive, whatever that
means, and that it is photo safe in accordance with
ISO 18616.

Unlike the old Scotch cellophane tape, it doesn't turn
into sticky brownish goozle after it gets a few years old.

Tape thickness is pretty important because adding additional
layers every layer of winding adds up pretty quickly. You
can reduce the thickness by only putting a small tab of tape
on the cross over from the flyback winding method, and at
every tap-off point.

HV resistance is not quite so important because there
is only 1.6V per turn in these transformers, so at most
you get 200V, or so differential.

-Chuck Harris




On Sat, 17 Feb 2024 10:21:07 -0800 "Roy Thistle"
<roy.thistle@...> wrote:

On Sat, Feb 17, 2024 at 08:35 AM, Dave Wise wrote:

double-stick tape

Where 'double-stick' = double-sided: referring to tape with adhesive
on both sides Then, you can get double-sided polyamide tape. (not
saying you need that... and not saying you don't want that.) The
adhesive is either silicone based, or acrylic based... where acrylic
adhesive is water based (mostly) and silicone adhesive is not water
based (mostly). I suppose if you want to avoid acrylic... then you'd
want an 'acid free' or 'neutral cure' silicone.

I've used 1 mill PFT='polyamide film tape' ... which about 1/4 the
diameter of 38 gauge wire. (check that) There is also the thickness
of the adhesive to take into account. Kapton tape is PFT; but
according, at least, to Dupont: Kapton is PFT; but, not all PFTs is
Kapton There is at least some variation in high temperature
performance? 300 F to 400 F for many PFTs... whilst Kapton can do 300
C to 400 C

Anyway... on Amazon... generic PFT is about 10X as expensive (sans
shipping) as from China (free shipping to here)... and the Amazon
stuff is probably from China anyway. You can get (probably good
quality?) PFTs on Mouser or Digikey;but IME, they are usually single
sided, for use in wave soldering.

On Sun, Feb 18, 2024 at 02:35 AM, Dave Wise wrote:

I used a sewing needle stuck into a dowel as my nozzle.? Before starting, I covered some dental floss in valve grinding compound and ran it through the eye to polish it a bit.

That's a terrific idea! Years ago I hacked a coil winding machine using an obsolete dot matrix printer mechanism and a microcontroller. It does a nice universal winding but the biggest problem I encountered was tensioning the wire and the design of the "finger". Now I'll revisit it with that idea in mind.

Thanks!

Morris