Scott 130 power transformer fix revised.

Magnet wire is available anywhere. Paper is just any low acid paper. Masking tape. I use a micrometer to measure wire diameter. The ARRL manuals from the 40's, 50's, 60's and 70's has all the information you need about wire gauge and how to wind transformers.

I know that you can get it many different places. I was asking from the
standpoint as to whether or not you had a preference.

The hardcore amatuer radio people wind their own transformers a lot. You can make a winder. I showed a picture at the beginning of my home made one. It works very well, in some ways better than the purchased units.

What youre doing looks real good. I was going to turn you on to a unit
someone was trying to sell for parts on ebay. But it looks like you have the
situation well under control :thmbsp:
 
Cut the wood core to the size of the transformer core
You'll have to explain this one again... So, I'd measure the dimensions of the core and cut two chocks of wood to the same size?

Depending on size, i like to make the wood mockup in three pieces or three layers, if you will. That way, when I'm done wrapping paper and glue to make the bobbin I can drive the middle piece out and the two outer ones will collapse. It's easy and doesn't wreck the bobbin you just made. Be aware that the glue saturated paper will shrink slightly when dry so you want to make the wood form slightly larger, not a lot, but a bit. You can experiment, they are easy to make. If the form is too small simply wrap some paper on it before you start your bobbin. Standard paper is about .004". If you're doing this you need a dial caliper or a micrometer to measure wire and paper so you can fit everything back together.

OK, good tip, but the stackup of those three pieces are to be of equal volume of the core?

Like this? (quick sketch)

O8o4VZZ.jpg
 
The wood model for winding a bobbin has the same outside dimensions as the core of the transformer iron, the part the windings will be wrapped around after assembly. You can certainly use wedges, but a thin piece of wood sandwiched between two thicker ones is a lot easier to manufacture correctly and will work fine. You won't have any trouble driving the center piece out if you keep it small and don't wrap everything too tight. Remember, the bobbin will shrink as it drys anyway, or will at least try to. I hope I am explaining correctly. I didn't make a bobbin so I don't have any pictures of doing it. I do have some extras around here from other transformers, I'll try and find them.
 
The wood model for winding a bobbin has the same outside dimensions as the core of the transformer iron, the part the windings will be wrapped around after assembly. You can certainly use wedges, but a thin piece of wood sandwiched between two thicker ones is a lot easier to manufacture correctly and will work fine. You won't have any trouble driving the center piece out if you keep it small and don't wrap everything too tight. Remember, the bobbin will shrink as it drys anyway, or will at least try to. I hope I am explaining correctly. I didn't make a bobbin so I don't have any pictures of doing it. I do have some extras around here from other transformers, I'll try and find them.

Ooh, ok, I get what you mean about the three pieces now. I had the location incorrect.

Does the thickness of the wood bits matter?


Sorry for going so far off-topic! :eek:
 
Here's a couple pictures of a bobbin I think I made for my 2500 volt Acoustat power supplies. This one actually shrunk too much which is why I have it. It's about 2" by 2" by 2" long.
 

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Ooh, ok, I get what you mean about the three pieces now. I had the location incorrect.

Does the thickness of the wood bits matter?


Sorry for going so far off-topic! :eek:
I don't think you're off topic at all. The post is to show people they can rewind a transformer. Best Regards to you and thanks for all the questions. Makes me glad I bothered to take the pictures. Wasn't sure anyone cared .
 
I have a good number of burned up power and outputs from various vintage pieces you interested in some work? If so give me a call 810-287-6135

Great Thread!

Craig
 
I don't think you're off topic at all. The post is to show people they can rewind a transformer. Best Regards to you and thanks for all the questions. Makes me glad I bothered to take the pictures. Wasn't sure anyone cared .

Oh, I'm excited that you shared!

I'll need to trundle down to the machine shot and make my own winder like your purchased one (with the threaded carriage + pulley setup), but maybe build a single/double idler in so I can reverse the direction during winding.

:scratch2:

Wood goes on the narrow ends, right, like this?

7PCMURo.jpg
 
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Moderators:
I nominate this thread to be a sticky. I do wonder the following though:
1. If stanko would like to retitle it. Essentially it's a transformer winding overview and the title is misleading of where the thread has gone.
2. It's a good question whether it should be a sticky here in tubes or perhaps in DIY.

This is one I'd like to be able to refer to later.
 
Some pictures of a hand wound quick core (Bobbin to some) for winding. I didn't use glue, just wanted to show the procedure. This shows the proper orientation of the wood. You want to be able to see all the pieces while winding, an end view sort of speak in the drafting world. I just grabbed two pieces, three is easiest to take apart later.
 

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Moderators:
I nominate this thread to be a sticky. I do wonder the following though:
1. If stanko would like to retitle it. Essentially it's a transformer winding overview and the title is misleading of where the thread has gone.
2. It's a good question whether it should be a sticky here in tubes or perhaps in DIY.

This is one I'd like to be able to refer to later.
I don't know how to do any of those procedures.
 
Moderators:
I nominate this thread to be a sticky. I do wonder the following though:
1. If stanko would like to retitle it. Essentially it's a transformer winding overview and the title is misleading of where the thread has gone.
2. It's a good question whether it should be a sticky here in tubes or perhaps in DIY.

This is one I'd like to be able to refer to later.

I would love for this to happen!


Some pictures of a hand wound quick core (Bobbin to some) for winding. I didn't use glue, just wanted to show the procedure. This shows the proper orientation of the wood. You want to be able to see all the pieces while winding, an end view sort of speak in the drafting world. I just grabbed two pieces, three is easiest to take apart later.

AH! I completely understand now!
 
Super job Stanko! Proof's always in the puddin'.......

No doubt we've all got some transformers we could "repurpose" for better use. Your thread shows just what is possible, and with the wisdom from practical experience to boot. Thanks for sharing what you've learned, and passing on your tips!

Dave
 
Absolutely outstanding! Just when I think I'm getting my head around all this stuff, up pops another skill to learn. Gotta go look for some old transformers . . .

Thanks for showing us Stanko. :thmbsp:
 
How close did you come to the desired voltage?Looks fantastic!
My calculations pointed to around 91 or 92 winds for 15 volts at the filament series groups. I had room and wire for about 105 so I put them all on there. I ended up with 18 volts which I reduced to 15 by using 2 10 ohm resistors instead of 1.35 ohm and 12 ohm as called for. I could have gone with calculated but I'm very happy with a little extra to drop across the filter networks. I suspect my ripple is much less than original while maintaining original voltages in the circuit.
 
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