Step Up Transformer for power supply

[dbishopbliss]

Could I use a Voltage Converter Transformer in a power supply? 

I only need between 250-300 Volts, but current required is close to 1 amps.

Hammond makes a toroid that will suit my needs, but it costs twice as much.  Wondering what the difference would be?

[Grainger49]

All transformers change voltages from one level to another.  Up or down, it makes no difference.  Since nothing is free, energy wise, the current drops proportionally with the voltage increase. 

What are the ratings, voltage and current, on the transformer you want to use?

[dbishopbliss]

The hammond is rated as:  Transformers 234V ct @ .96A 117V @ 1.92A - just shy of 1 amp.  Actual current I will be drawing for tubes is 0.5 amps.  The cost is $81.

I would think the voltage converter transformer could handle 1 amp of current (not sure how to tell).  The cost is $30.

I could go with the hammond, but it would be nice to save $50. 

[Grainger49]

Since you gave the specs of the Hammond:

Either side of the transformer can be wired to the appropriate or lower voltage than it is rated for.  So if you put 117V on that side the other side will supply 234V with up to 0.96A available.  If the secondary "draws" 0.96A then the primary will be running at 1.92A.

If you have the specs on the voltage converter I can help there.

[dbishopbliss]

Spec's I have are from the link I posted above.

# 500 Watt Maximum Capacity Heavy-Duty Voltage Converter / Transformer
# Dual Step Up or Step Down functionality
# Switch the transformer to 110V for use in USA to output 220V
# Switch the transformer to 220V for use in overseas to output 110V
# Input: 110V -> Output: 220V
# Input: 220V -> Output: 110V

They also have lower wattage transformers for less money if they would do. 

[Grainger49]

Got it.  I didn't recognize the links as links.  The transformer in question is about 500VA.  That means the volts times the amps on each side of the transformer will be 500, actually a little less.  That is a goodly amount of current.

The transformer is good for 4.66A on the 120V side and 2.33A on the 220V side.  It will deliver what you need after rectification and filtering.  That would be the square root of 2 times 220V less some minor voltage drops.

[2wo]

Take a look at

[Dyna Saur]

Just make sure that your step-up trannie has separate primaries and secondaries, some of the cheaper ones are simply auto-transformers, with one tapped winding, which means that the higher voltage output is still "hot" as it has a more or less direct connection to the AC power line.  

I've used 115/230VAC step-ups, and 115/115 isolation trannies for B+ supplies on several occasions. The isolations need to use a voltage doubler, to obtain B+ of  about 275-300VDC, the step ups require a fullwave four diode bridge, for the same range of B+ voltages. .

Check out AnTek (johnango on ebay) he has a wide range of  very reasonablly priced toriods, including  120+120VAC: 120+120VAC four-winding toroids which can be used for step up or step down purposes.  If you're not drawing ehavy current, then three windings could be connected in series to make it a 120:360VAC step up.  He also has a wide range of 50, 100, 200, 300 and 400VA tube PSU toriods of a wide range of secondary voltages.   He is locaed in NJ, though I suspect that the trannies are manufactured over in Asia, which isn't a problem for me....

http://www.antekinc.com/index.php

/ed B in NC

[dbishopbliss]

Just make sure that your step-up trannie has separate primaries and secondaries, some of the cheaper ones are simply auto-transformers, with one tapped winding, which means that the higher voltage output is still "hot" as it has a more or less direct connection to the AC power line.

I've used 115/230VAC step-ups, and 115/115 isolation trannies for B+ supplies on several occasions. The isolations need to use a voltage doubler, to obtain B+ of  about 275-300VDC, the step ups require a fullwave four diode bridge, for the same range of B+ voltages. .

Check out AnTek (johnango on ebay) he has a wide range of  very reasonablly priced toriods, including  120+120VAC: 120+120VAC four-winding toroids which can be used for step up or step down purposes.  If you're not drawing ehavy current, then three windings could be connected in series to make it a 120:360VAC step up.  He also has a wide range of 50, 100, 200, 300 and 400VA tube PSU toriods of a wide range of secondary voltages.   He is locaed in NJ, though I suspect that the trannies are manufactured over in Asia, which isn't a problem for me....

http://www.antekinc.com/index.php

/ed B in NC

I sent an email to AnTek already, haven't gotten a reply yet.  I have dealt with him before. He has a lot of transformers that are not listed on his site.

How would I tell if the step-up transformer has separate windings?  I'm guessing that since these are cheap they probably do not.

[JC]

An auto-former would generally share a single common lead on both the "primary" and "secondary".