Weird Transformers (not the movie)

[guidoilieff]

A friend of mine gave me this "electric tension stabilizer" for its housing. I thought I could use the transformer but this is what I found






In the last picture you can see "220v, 110v, Neutral, 2, 1, 3, 4. There is nothing on the other side. I guess the schematic would be like this because there is continuity with the primary winding:


I want to know how to test it and use it as a "traditional" transformer with or without central tap. Does it make any sense?
I know how lethal it could be.



Aaaaand I have 4 of these puppys:



50w and 12v is 4 amps if i'm right. I wonder if I can sacrifice amps to reach 24v. Is that a reasonable analog cheap miraculous option?


Thanks for your time!

[R.G.]

1. Do not do this. The danger of electrocution is too high.
2. Read #1 again.
3. Read #1 again.
4. Start over with #1.

There is no good way to tell from the outside whether there is a simple way to remove the connection between the AC mains voltage and the secondary, or if once you've done that, it is >>safely<< insulated from the AC mains voltage. This thing could electrocute you immediately, or sometime later when it breaks down from insufficient internal insulation, or electrocute someone you care about years from now.

There is no safe enough way for you to test it and use it as a normal transformer if it shows continuity with the AC mains winding. Even if it works OK at the start, there is no knowing its long term safety.

[guidoilieff]

1. Do not do this. The danger of electrocution is too high.
2. Read #1 again.
3. Read #1 again.
4. Start over with #1.

There is no good way to tell from the outside whether there is a simple way to remove the connection between the AC mains voltage and the secondary, or if once you've done that, it is >>safely<< insulated from the AC mains voltage. This thing could electrocute you immediately, or sometime later when it breaks down from insufficient internal insulation, or electrocute someone you care about years from now.

There is no safe enough way for you to test it and use it as a normal transformer if it shows continuity with the AC mains winding. Even if it works OK at the start, there is no knowing its long term safety.

Thanks, I won't.

Do you know a way I can make the 2nd transformer I posted to output 24v?

[thermionix]

Do you know a way I can make the 2nd transformer I posted to output 24v?

You can put 440v on the primary.  (Don't do that, the primary is not rated for 440v)

[R.G.]

Do you know a way I can make the 2nd transformer I posted to output 24v?

Yes. Use two of them, and parallel the primaries, but series connect the secondaries.

[Rob Strand]

Do you know a way I can make the 2nd transformer I posted to output 24v?

If you ultimately want to rectify and filter the 24V AC to produce a DC rail then you can use one 12V AC transformer with a doubler circuit for the rectifier and filter.  The DC output will be like you had a 24V DC transformer.  The maximum current will be half what you would get from a 12V transformer.  (ie. you can't get something for nothing.)

Have a look here,
http://www.diystompboxes.com/smfforum/index.php?topic=119409.0

[guidoilieff]

Do you know a way I can make the 2nd transformer I posted to output 24v?

If you ultimately want to rectify and filter the 24V AC to produce a DC rail then you can use one 12V AC transformer with a doubler circuit for the rectifier and filter.  The DC output will be like you had a 24V DC transformer.  The maximum current will be half what you would get from a 12V transformer.  (ie. you can't get something for nothing.)

Have a look here,
http://www.diystompboxes.com/smfforum/index.php?topic=119409.0

That's what I want to do. The doubler should be before rectifying right?

Is my math ok? 50w at 12v is like 4 amps? seems too much for the size of the transformer, its from dichroic lamps.

[Rob Strand]

That's what I want to do. The doubler should be before rectifying right?

I'm not sure what you are asking here.   The double is formed by connecting diodes and caps in one of the ways mentioned on the link.  You can't separate rectifying and doubling.    The case where the two diodes connect together at the transformer follows the order transformer -> rectifier -> caps.

Is my math ok? 50w at 12v is like 4 amps? seems too much for the size of the transformer, its from dichroic lamps.

Yes.   50W, or more correctly, 50VA at means full current is 50VA / 12V = 4.17Amps.
However you can only pull 4.17amps with a *resistive* load.

When you use a transformer with a rectifier and filter you must decrease the current by a factor of about 1.8 ie.  IAC/IDC = 1.8.    (FYI: Sometimes you will see this factor as 1.6, 1.62, 1.68;  the situation is based on many factors.)
So that means 4.17 / 1.8 =  2.3A.     
If you use a doubler it will be about half that again so 1.15A.   

Is my math ok? 50w at 12v is like 4 amps? seems too much for the size of the transformer, its from dichroic lamps.

Is 50W or 50VA marked on the unit? [Edit: (OK I can see the image again 220V 12V 50W)]
You can *estimate* the power from the resistance of the primary windings and the AC input voltage