8mm Forum: Custom Made Transformers

This is topic Custom Made Transformers in forum General Yak at 8mm Forum.

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Posted by Bob Pucci (Member # 8) on April 14, 2013, 11:37 AM:

I have to ask this question.Does anyone know a person or a company who will make a custom transformer.The reason being,I bought a jukebox wallbox on ebay and inside of it the transformer was missing.The key was missing to get inside of it,so the person who auctioned it didn't know that it was missing.Thanks

Posted by Pasquale DAlessio (Member # 2052) on April 14, 2013, 12:22 PM:

Try goggling it! Google is your friend [Wink]

PatD

Posted by Steve Klare (Member # 12) on April 14, 2013, 02:54 PM:

I think you probably could find somebody willing to do a custom transformer for you, but as they say "Given enough money you could fix the Titanic."

Making a brand new transformer involves having an engineer do the design work, and then having somebody sit at a winding machine and put the correct number of turns on the windings and then assemble it and test it. (Time and money, LOTSA money...)

-however!

There are thousands of different standard transformers available in catalogs.

With the same information that would be needed to develop one from scratch (Input voltage, output voltage(s), output current(s), size, mounting configuration...), there's a decent chance you could find a replacement much cheaper.

The odds are decent the one that was in there was a standard product in the first place. The jukebox manufacturer wouldn't want to reinvent the wheel (and take the technical risk) by making their own transformer when they can buy a month's worth of ones they know will work for wholesale prices and need to worry about nothing more than where to stock them until they are needed for production.

That way they could dedicate themselves to being a good jukebox manufacturer and leave being a good transformer manufacturer to somebody else.

What do you know about the part you are missing?

Posted by Bob Pucci (Member # 8) on April 14, 2013, 03:21 PM:

Thanks Steve and Pat

Pat I did google it and couldn't find what I want.

Steve What I know about it looking at the schematic is:

You feed in 28 vac from a external power supply to a terminal strip.From there the 28 volts goest the primary windings of the transformer.The primary also has a center tap in it of 6 volts ac to run the 6 volt lamps.

Now this is what iI can't figuare ouy.The secondary winding (voltage) goes to a full wave bridge which the voltage is rectified and filtered to produce +13 VDC.It doesn't say what the secondary voltage is.

The 13 vdc is what powers the wallbox.

Posted by Steve Klare (Member # 12) on April 14, 2013, 03:35 PM:

Well,

What you ultimately need to have is 13 Vdc. Do you know how much power you need? (This is a key question.)

Posted by David Ollerearnshaw (Member # 3296) on April 14, 2013, 04:14 PM:

Take a look here it could be of use Jukebox parts

Posted by Bob Pucci (Member # 8) on April 14, 2013, 07:16 PM:

Steve

The power I need is 11.5 watts and current is .45 amps.

David I know of that web site.I have brought things of him.Thanks

Posted by Steve Klare (Member # 12) on April 14, 2013, 07:23 PM:

OK,

That's a fairly small transformer.

Is the 13 volts DC just coming directly from the rectifier through a filter or is there some kind of voltage regulator in between?

Posted by Bob Pucci (Member # 8) on April 15, 2013, 06:29 AM:

The 13 volts DC comes filtered from the rectifier than goes on to other circuts.It also goes to a voltage regulator to produce 5 volts DC.

Thanks Steve for trying to help me.

Posted by Steve Klare (Member # 12) on April 15, 2013, 10:29 AM:

Not done trying yet!

The real fly in the ointment here is the 28VAC primary. There are literally thousands of transformers with 115VAC primaries, but like five with 28VAC. (None of them are what you need, either...)

Are you very sure about this? If you are do you think it would be possible to skip the 28VAC altogether and use 115VAC transformer(s)?

I'm glad you have a schematic, doing something like this without one is just blundering around in the dark

Posted by Lee Mannering (Member # 728) on April 15, 2013, 12:51 PM:

Just a word for anyone in the UK looking for custom trannys. There are plenty of firms offering this service and will accommodate just about any project. I’ve had jobs done local to me and particularly a custom tranny which fitted perfectly in the bottom of a Pathe Vox to supply just about any reasonable voltage tappings needed. You will need to know the amps you need as well particularly when driving AC motors but very rewarding when a ‘soup up’ is completed and you squeeze the max out of a 1930’s sound projector.

1/ Be clear about the physical size you want the transformer to be and mounting it
2/ List the voltages (tappings) you need clearly
3/ Be clear about the amps required and its worth over estimating these...say 10%

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