Lowering AC output of Xformer (low voltage)

[Alf]

I would like to use this small Xformer I have 220 volts to 15 volts .
Here in Europe we now have 230 volts and I get 16,3 volt s from it and would like to lower it to 14 volts ac . I need this voltage for a Boss drumcomputer
DR880 . Can I just use a couple of powerresistors in series. The current draw will not me more than 800 mA.

Thanks , Alf

[Tom Phillips]

Alf,
If the current drawn by the DR880 is a steady value then, yes, you can lower the voltage by adding resistance. You only need one resistor unless you want to use two to make up the proper value. If the DR880 draws different amounts of current at various times as it operates then the voltage at the input will also change.
It may be easier to buy the proper transformer. That's up to you depending on how you want to spend your time and money.
Regards,
Tom

[Don Moose]

Would it be practical to put the following badly-described zener circuit in the primary - where the current will be (230/16.3) * 0.800A?

You'll need two series assemblies of a 17V (or so) Zener and a 1N400x diode, cathode-to-cathode. Put those two assemblies in parallel, such that one zener is next to the other 1N400x (some people call this anti-parallel). Then put that parallel assembly in series with one leg (someone advise whether Hot or Neut would be preferable - I'm thinking Hot) of the PRIMARY, to lower the input voltage; in turn, lowering the output voltage.

Coherent?

[Sock Puppet]

Originally Posted by Don Moose

Coherent?

A bad idea if one of the zeners fails Don....

The correct supply is only around 18 G.B.P. or there's this one on
ebay.co.uk, item number 300138243497 - 1p bid so far.

S.

[Alf]

I'll first try the resistors , I don't know if the current is the same all the time.
And it is better to use the proper powersupply and my friend ordered one but it could take a month or so to arrive.

Thanks , guys

Alf

[Ptron]

You also might want to check the specs of the Boss thingy. Devices often have a range of input voltages that they can handle. Maybe it can handle the higher voltage.

[zoranrataj2000]

Hi!
Open your Boss,found where you have power supply diode or gretz,put before or after diode or gretz-bridge in series 3 diode which handle 1,5A current and this is.

Do not use any ressistor and something like that.

You can do this outside without opening Boss too.Just cut one wire and insert between in series 3 diode and try.If it is not working at all, turn around all 3 diode and will work.All 3 diode have to be in the same direction.
This is easy way and only electrical correct.

You can write me and I send you picture how you do this.

If you do not like this, you must change transformer.

LP,Zoran

[Tom Phillips]

Originally Posted by zoranrataj2000

...
You can do this outside without opening Boss too.Just cut one wire and insert between in series 3 diode and try.If it is not working at all, turn around all 3 diode and will work.All 3 diode have to be in the same direction....

That will only work with a DC supply.
Alf said that he was trying to reduce about 16.3VAC to 14VAC.
If you want to reduce AC voltage by the series diode method then you need to use back to back diodes.
Regards,
Tom

[Alf]

Thanks Tom for putting that right.

Yes , it's the 14 volts AC I want. Today I looked around in my local electronics supply shop and the didn't have this odd xformer voltage either.
So my friend will just have to wait for another adaptor coming in ( probably again from China !)
The thing went bust for no particular reason. Personally I don't have too much confidence in these cheapo Chinese stuff.
I always try to go for quality but then I'm an oldfashioned person so it seems.

Regards, Alf

If any of you have any other ideas please , let me know