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
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
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).
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...
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
JAPAN VOLTAGE CONVERTERS - One Year Warranty
Last edited:
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.
to calculate current look at the power consumption of your device. Power is Voltage times current, therefor current is power divided by voltage.
P= E x I
I = P / I
if 110volt device is 50 watts then
I = 50/110
or about 1/2 amp
so you need an auto transformer that is 220 volt times 1/2 amp or about 100 watts. Remember an autotransformer only has one winding.
P= E x I
I = P / I
if 110volt device is 50 watts then
I = 50/110
or about 1/2 amp
so you need an auto transformer that is 220 volt times 1/2 amp or about 100 watts. Remember an autotransformer only has one winding.
Thanks for the link. I will be following that thread. Who knows it will turn out to be something very useful or doable. Tho currently I think the solution is too complex, or insane
Thanks multisync and sreten. I didn't know of this autotransformer technology before. Now I understand that what I did was normal and common, it was just that the ordinary transformer not designed for optimum current and size. Then it is then possible to wind a high current autotransformer (single winding, non flux/induction based)) even for amplifier purposes (around 3A to 4A), using bobin/donat core for example.
Thanks for the link. I will be following that thread. Who knows it will turn out to be something very useful or doable. Tho currently I think the solution is too complex, or insane
Oh, BTW I forgot to mention one of the many benefits of this scheme: it also acts as a regulator vs. line variations, because the conduction instants are defined by comparing the input voltage to fixed references, rather than using a fixed conduction angle.
This also means that it will make your transformer a universal input PSU, operating seamlessely from 100 to 300VAC.
Don't try this: even in an autoformer, the flux is all important.
You will end up with a giant electric heather....
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.