What is the elegant way to convert 220? to 110V?

[Jay]

I have a good toroidal transformer which unfortunately is 110V input. I want to use it for amplifier supply but I don't like the idea of putting a big step down transformer in front of it. Is there any creative way?

I have CD player that also uses 110V primary (yes, Japanese stuffs). Instead of using step down transformer that usually is big, I want to use a small 2A transformer, but only using the primary winding...

The primary winding will have 0-110-220 connections, so I will use 0-220 for the input and 0-110 for the output (to go to 110V transformer). What could be the problem of this approach? How to calculate maximum current?

Thanks

[sreten]

Hi,

most mains transformers have two primaries, wired in
series they are 220v and wired in parallel they are 110V.

If its really 110V only get another and wire the
primaries in series and the secondaries in parallel.


rgds, sreten.

[Jay]

Originally Posted by sreten

Hi,

most mains transformers have two primaries, wired in
series they are 220v and wired in parallel they are 110V.

If its really 110V only get another and wire the
primaries in series and the secondaries in parallel.


rgds, sreten.

Thanks sreten,

This transformer is a big potted toroid, from Japanese amplifier. Of course I don't have another similar transformer. But if I wired the primary in series with 3A primary of an EI transformer (only the primary, the secondary will be left unused), isn't the maximum current will be decided by the 3A primary?

If I have to use a step down transformer, is there any kind of benefit to the sound of the amplifier? I have a feeling that there will be one. May be there could be some kind of filtering. Or I can use caps between the two transformers (LC filter).

[pjp]

The most elegant solution is a nice step down transformer.

If you want further justification, put in a shield and call it a mains borne noise suppression device.

[metalsculptor]

Being Japanese it will be 100V input, do not wire the primaries in series the unloaded one will behave like a reactor and may even go into saturation.

Go with the step down transformer ugly but well proven and it will not affect the sound, just get the grounding right.

[Jay]

Originally Posted by pjp

put in a shield and call it a mains borne noise suppression device.

Hehehe rite! An integrated mains purifier...

[Jay]

Originally Posted by metalsculptor

Being Japanese it will be 100V input, do not wire the primaries in series the unloaded one will behave like a reactor and may even go into saturation.

Go with the step down transformer ugly but well proven and it will not affect the sound, just get the grounding right.

What a pity. I have plenty of 220V transformers but no step down transformer. Cannot justify to buy one. Better leave it unused for the moment...

[Elvee]

Have a look here for a possible answer.

[multisync]

smaller than a stepdown transformer is an autotransformer. An autotransformer has only one winding, basically 2 - 110volt windings in series. They are normally used for 110 volt to 220 volt or 220 volt to 110 volt for tourists that are traveling. Pick one that has a correct power rating or higher for future needs. Here is a link up to 3kw is available

JAPAN VOLTAGE CONVERTERS - One Year Warranty

[sreten]

Originally Posted by Jay

I have CD player that also uses 110V primary (yes, Japanese stuffs). Instead of using step down transformer that usually is big, I want to use a small 2A transformer, but only using the primary winding...

The primary winding will have 0-110-220 connections, so I will use 0-220 for the input and 0-110 for the output (to go to 110V transformer). What could be the problem of this approach? How to calculate maximum current?

Thanks

Hi,

There is no problem doing the this. Simply put the secondary will take
up space more usefully used for the primary, which can act as an
autotransformer, real autransformers are cheaper and more efficient,
as the lower winding of the two 110V sections should be a lot thicker
to allow twice the nominal input current (at ~ half the voltage).
Normal windings are not optimised for this case, unlike autotransformers.

rgds, sreten.


rgds, sreten.