Need help with a toroidal transformer

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
Hope someone has a data sheet or catalog that can help me with an old toroidal I have had. Bought it years ago at a flea market, brand new in a sealed box, but with no documentation. It is a Amveco AA-28263 did a search online for it and the only real information isn't what I was looking for.

The wiring color code isn't like any other I can find. The wires for the primary are easy, it's the secondary that is not normal. There are 5 wires, two white colored and a gray that are I believe the secondary out puts, but there are 2 light blue ones that are a smaller gauge. When I test them using a meter they are all 5 connected together. The label says it is center tapped 57V or two 28.5V. But what would the 2 blue wires be used for? I don't want to just plug it into the mains until I understand the 2 extra wires. Hope some one knows more about this.
 

MaxHeadRoom

Joined Jul 18, 2013
19,729
If you know the primary, I would put 120vac on it and test the voltage on all the rest, you may get an idea whether the primary is 120v or 240v, one should give you the known voltages.
Then check the two blue.
The beauty with Toroid, is it is very easy to wind you own, or modify the existing.
What is the OA core dimensions?
This will give you an idea of the (k)Va.
Max.
 

crutschow

Joined Mar 14, 2008
24,101
You might want to connect an incandescent bulb in series with the primary when you first connect it to the mains, to minimize the chance of zapping something. :rolleyes:
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
Thank you all for answers. My concern was the two blue wires and that all of the secondary wires have continuity with each other. Probe on one gets continuity on the other four, never saw that before. But after I cut some of the translucent plastic wrapping that covers the whole thing off of the area of the label, it says it is protected by "Thermik SO6". Googleing that says it is a self resetting thermal switch, with NC contacts. But so far haven't figured out why it has continuity with all of the secondary outputs?

Max, I do know the VA, 120V, 288VA for the primary and 267 VA on the secondary. Can't easily add or subtract winding's on this one, it has the center filled with either Epoxy or some kind of urethane.
 

MaxHeadRoom

Joined Jul 18, 2013
19,729
Max, this one, it has the center filled with either Epoxy or some kind of urethane.
I had one similar to this and managed to gently knock the centre core out.
If the thermal switch has continuity to all other secondaries, measure the voltage to all the other ends and see if for one there is zero voltage difference to the blue, IOW which end it is connected to.
Max.
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
@ MaxHeadRoom, OBW0549, crutschow Figured it out, wish I knew what this was used in, the only real online soruce of information was ESP in a transformer discussion, so maybe from an amplifier.

There were 5 secondary wires: blue - white - gray - white - blue. So when the primary was powered up with 125VAC the following voltages were found, all without any loading -
blue to blue = 61V
blue to white = 15V
blue to gray = 30.5V
white to white = 31V
white to gray = 14.5V

When I opened up the gray wire cover that was over it there was two wires inside. So it seems like this has two secondaries with both of them center tapped. That is why all of the secondary wires had continuity with each other, that continuity is why I didn't want to just power it up without a little more knowledge.
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
So do you have a use in mind? :cool:
Max.
Yeah, I need a transformer of around 30volts and 10 amps, to power my new ZVS(zero voltage switching) induction heater. I want to make it into a DIT "BoltBuster". https://boltbusterinc.com/ The power supply will be separated from the induction heater by a wire not an all in one like the commercial one.

I was going to try and rewind a MOT, but couldn't find any hard facts on what VA you can get out of one when doing a rewind. Any ideas of what is possible with a MOT?

Over the winter I want to restore an old Speedex garden tractor I bought. Over all the Speedex is pretty good shape with good original paint and decals so to get the few bolts lose that need it I don't want to use a torch and ruin the paint. They were made close by here in Ravenna, OH.

https://en.wikipedia.org/wiki/Speedex_Tractors
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
They call the induction heater 1000W but most don't use the full 1K. The few that I've seen use 300VA to 500VA.

Don't the MOT welders use a very small voltage at high amps? I was going to just buy a toroid from Antek when I remembered the one I started this thread about and went looking for it in my transformer box. I have a box with transformers and low volt power supplies I've gathered up over the years.

Using the available trans will save me $ I don't have at the moment. Social Security living sucks. The way I figure it the trans at the start of the thread when I separate the secondaries will give me 9.37A @ 28.5V from the 267VA of it. Or is my math wrong?
 

MaxHeadRoom

Joined Jul 18, 2013
19,729
Don't the MOT welders use a very small voltage at high amps?
But so does induction htrs, typically.
Essentially the coil is a 'step down' , I have worked with industrial types, but never actually come across the 'Bolt Bust' types but apparently just a portable version, this one does not seem to be that high a Va!
I would think that your Toroid should be ample, What are the dimensions?
Max.
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
But so does induction htrs, typically.
Essentially the coil is a 'step down' , I have worked with industrial types, but never actually come across the 'Bolt Bust' types but apparently just a portable version, this one does not seem to be that high a Va!
I would think that your Toroid should be ample, What are the dimensions?
Max.
That link is where I decided to make instead of buy. The ZVS he used though is one that works only at 12V or less if I remember right. Ebay has two types one for ~12V and the one I got that is good to 48V, but both are called 1000W ZVS heaters.

The trans is back out in the shop, but just guessing it is around 4" diameter X 2" thick and weighs at least 4 pounds, maybe a little more. The VA is one thing that is on the label. But no wire diagram, but have it figured out.
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
New questions about transformers. What is the difference between a standard step down transformer and a "filament" transformer? The Google net doesn't seem to know. Can a filament transformer be used with a bridge rectifier to power a circuit? Or is there a reason not to do it?
 

MaxHeadRoom

Joined Jul 18, 2013
19,729
I have serviced many tube (valve) amps/radios/TV's and any filament transformer just supply's the 6.3v or what ever is needed for the the cathode heater.
Standard EI generally.
I once built a tube tester and modified a transformer to cover all the different filament voltages.
Max.
 

Thread Starter

shortbus

Joined Sep 30, 2009
7,348
That is the same thing Google comes up with. But Hammond makes filament transformers of higher voltages up to 80V in their 165 series. I knew that they were used with tube/valve situations but wondered what made them different enough that they were called out by a different name?
 
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