Yaqin MS23B Step Down Autotransformer for UK Mains?

[pikebobstar]

Hi All,

Thinking of using one of these for a stable 220V supply? http://uk.rs-online.com/web/p/autotransformers/2932656/

Will the amperage rating (1.6/0.8A) be sufficient.

I used one of these Autotransformers for a Little Dot Mk3 following an online recommendation and it worked a treat with no issues for a couple of years more or less constant use.

Your thoughts most welcome

[awkwardbydesign]

A smple and cheap method is to use a bucking transformer. This is what I and others have done. But a dropper resistor in the heater circuit may be all that is needed in the Yaqin. Anyway, here is some info on the bucking transformer. http://sound.westhost.com/articles/buck-xfmr.htm
I have made several of them, each in an oak box. Add a fuse if you like.

[pikebobstar]

Well, Just to advise I went again with the Block step down transformer so supplying the Yaqin with a regulated 220V power supply @ 0.8-1.6A and have noticed the unit is running cooler. Also, a slight whine I had from the transformer outer metal casing has gone. I cant be certain it's the difference in voltage/heat or to do with some hours now being put on it.

This little valve phono pre is just getting better and better as time goes on. Recommended.
Cheers

[lurcher]

Just to answer the original question, no the transformer in the first post is not suitable for producing 220v from 230v mains, its a 2:1 ratio so your amp is seeing 120v now. You would either need a custom would autoformer or use the bucking method shown.

[awkwardbydesign]

Just to answer the original question, no the transformer in the first post is not suitable for producing 220v from 230v mains, its a 2:1 ratio so your amp is seeing 120v now. You would either need a custom would autoformer or use the bucking method shown.

I just had another look at that transformer. It looks like a step-up! So 115v in and 115/220/230 or 240v out. So totally wrong. I missed that first time round.

[lurcher]

Actually, I just had a look as well, its misleading, the spec shows primary and secondary, but its described as a autoformer. I think it will just be a 0-115-220-230-240 autoformer. So I was wrong, it will be perfectly suitable to go from 240v to 220v

[awkwardbydesign]

..

[pikebobstar]

Hi and thanks for the comments/advice.

As I mentioned, I used this transformer to step down 240-220V on a Little Dot Mkiii headphone/preamp and it worked just fine for 2 years. Recently sold it and had no issue reported from the new buyer.

I have read the supplied data sheet cover to cover a few times and am certain it IS a step down autotransformer. I also believe the internal fuse in the Yaqin is 1A? according to its data sheet. So I guess it will match ok. Time will tell.

Thanks again