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Author Topic: Homwbrewing a toroidal transformer  (Read 5572 times)
KC2ZPK
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« on: February 16, 2012, 07:55:26 PM »

So I want to play with some power transformers, but I want to use toroidal cores. What or where is a good starting point for information on what type and size of cores?
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John
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DAVER
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« Reply #1 on: February 16, 2012, 09:26:52 PM »

What transformation are you trying to make and for what purpose? A lot of it hinges on using the right material for your application.

73,
Dave, KD2AKC
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KA4POL
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« Reply #2 on: February 16, 2012, 10:05:06 PM »

Some basic information may be found here: http://sound.westhost.com/xfmr2.htm
However, as said before, it depends on what you want to transfer, frequency, voltage, current. Basically it's fairly easy but sometimes it makes more sense to buy ready made ones.
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KC2ZPK
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« Reply #3 on: February 17, 2012, 06:06:56 AM »

Well to start I just want to learn a little, but 2 transformers interest me.
1) HV transformer for tube amps
2) 120AC to ??DC for shack equipment requiring DC supply.

I am sure there is commercially available equipment out there, but this is a learning hobby, right? Smiley
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John
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KA4POL
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« Reply #4 on: February 17, 2012, 07:53:53 AM »

Try the demo: http://www.rale.ch/demo.htm
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W5FYI
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« Reply #5 on: February 17, 2012, 08:19:25 AM »

Take a look at microwave oven transformers; they can provide high voltage, as they are designed to do for the oven's magnatron tube and, reversed, can provide low voltage for that kind of application. Be careful, the high voltage can be lethal, and reversed they may need some current limiting resistance in series with the primary winding.

The ARRL handbook may have some information on winding transformers. I do know that many power transformers utilize a gap in the core to prevent eddy currents from developing and overheating things.

There are also commercially-available toroidal transformers designed for low-voltage power supply applications. I'd also check with Amidoncorp.com for additional information....

Good luck with your project.
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WX7G
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« Reply #6 on: February 19, 2012, 04:25:18 PM »

Toroidal transformers really don't lend themselves to homebrewing due to having to wind so many turns.

Having said that, 120 VAC step down transformers aren't that bad to wind. I have wound several using Variac cores/windings as the primary. You simply wind the secondary on top. Get an old or new variac, remove the rotor assembly and you have a pre-wound primary.

A HV toroidal transformer would be a nightmare to wind without the special winder that is used commerically. It looks like something out of a bicycle factory.

So, for 12 VDC power supplies the Variac trick is great.
« Last Edit: February 22, 2012, 03:22:24 AM by WX7G » Logged
AF6AU
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« Reply #7 on: March 01, 2012, 12:52:29 PM »

How much of your time is worth the $$$?
See these guys:
www.antekinc.com/

Chances are they have what you are looking for, and not too bad price wise.

JML/AF6AU
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BRIANBURNS
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« Reply #8 on: March 03, 2012, 11:01:54 AM »

Hello All,

AF6AU mentioned AnTek for toroidal transformers, and I just posted the following message on the boatanchors forum.

For those of us who want to homebrew with tubes, one of the toughest things is sourcing transformers. Has anyone had any experience with the AnTek toroidal transformer company, or its products? There was a post on AMfone four years ago that made it sound like they could make you most anything. I'm talking about power and modulation transformers for the typical 100 watt transmitter that we might want to build.

Cheers,

Brian Burns  soon to be K6UCD once again
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AC5UP
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« Reply #9 on: March 03, 2012, 11:27:48 AM »

http://www.hammondmfg.com/5cindex.htm
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BRIANBURNS
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« Reply #10 on: March 03, 2012, 03:28:02 PM »

Hello Nelson,

I checked out Hammond's "Classic" transformer line and the highest voltage one they seem to make is 500-0-500 @ 230ma. I'm thinking of a pair of 6146's in the final at about 750 v on the plates.

From AMfone:  "I just bought a 1KVA Antek power transformer for my HPSDR final. They make very nice stuff."

That sounds like  a whopper of a power transformer, though I expect that it is relatively low voltage! I've got an inquiry in to AnTek about power and modulation transformers that we tube-type home-brewers might like, and  will report back if I hear anything interesting.

Cheers,

Brian Burns
« Last Edit: March 03, 2012, 03:32:26 PM by BRIANBURNS » Logged
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