S5 Amp kit Power supply for UK

[Centural]

Hi I have a S5 electtronics kit which i am about to start building.
does anyone know what I should look for when changing the power supply from 120v to 240v. Sorry I'm a bit of a beginner on this ? Regards C

 

[fdegrove]

S5

Hi,

This is what I found on the manufacturers website:

The amplifier is designed to operate from 120 Volts 60 Hertz and may be plugged into a convenient outlet.

Since they don't mention any other primary windings on the xformer I assume you will need to buy a stepdown xformer:

Primary side 240VAC.(to your walloutlet)
Secondary side 120VAC.(in series with the primary of your amps xfromer)

Check the wattage on the xformer you have now and buy a new one with at least the same wattage rating.

Cheers,

 

[Burnedfingers]

There is one thing that Frank failed to mention... You could always give the kit to me since I am in dire need of tube gear and I have 120volt service in which to enjoy your kit.



Just kidding

Joe

 

[Centural]

100k ohms ??

Hi guys thanks for the info.

I've checked p wer xformer that comes with it and all i can find is that its output impedence is 100k ohms. ?

Maplins do a couple of valve amp xformers and one is rated 300 ohms and the other sais the "HT Secondary" is 0-240V @ 100mA

being a complete beginner which one is the nearest and/or best to go with this kit? and why? thanks C

 

[Burnedfingers]

I think what Frank has in mind is a simple stepdown transformer.
You plug it into your wall outlet and plug your amp/preamp into its
outlet. This way you don't have to purchase a new transformer for your kit amp. I'm sure these transformers are quite common in Europe and places like that where you have the 220-240 service on everything, otherwise us foreigners wouldn't be able to plug in our shavers or hair dryers.

Joe

 

[SkinnyBoy]

I have one.. does that help ya much??

 

[fdegrove]

XFORMER

Hi,

Yes,a stepdown xformer is what you need.

The best thing to do is to get one that is able to feed you amp with some spare power.

If you go into an electronics spares shop and explain to them what it is going to be used for they should be able to help you out.

Cheers,

 

[planet10]

Re: XFORMER

Yes,a stepdown xformer is what you need.

One of the weak points on this kit is the size of power xformer, so i wouldn'd discard the idea of just buying a beefier mains transformer with the appropriate secoundaries and get your 1st upgrade out of the way.

dave

 

[fdegrove]

VA RATINGS.

Hi,

Does anyone have an idea about the required va ratings for this Xformer?

If the original xformer is that weak David has a very valid point in replacing it altogether.

While were at it the B+ side of the amp can be upgraded too with some larger caps.

Admittedly I'm talking in the dark here...

Cheers,

 

[planet10]

schematic

i pulled this off their website

dave

 

[planet10]

and Data

what little i could find:

11MS8 --High-Mu Triode - Beam Power Tube

Characteristics

Data Source. . . . . . . . . RC-29
Heater or Filament Voltage . 11.6 volts
Heater or Filament Current . 0.45 amperes
EIA Base . . . . . . . . . . 9LY
Outline. . . . . . . . . . . 6-4
Prefered Substitutes . . . . None
Substitutes. . . . . . . . . None


Miniature type used in combined vertical-deflection oscillator and amplifier applications in tv receivers. Requires miniature 9-contact socket.

Capacitances and Design Maximum Values

Section. . . . . . . . . . Pentode
Plate Dissipation. . . . . 6 watts
Screen Dissipation . . . . 1.5 watts
Maximum Plate Voltage. . . 250 volts
Maximum Screen Voltage . . 200 volts

Section. . . . . . . . . . Triode
Plate Dissipation. . . . . 0.5 watts
Maximum Plate Voltage. . . 250 volts

An externally hosted image should be here but it was not working when we last tested it.

dave

 

[Centural]

re transformer

Hi guys Happy New Year!!

Thanks so far for the replies and help

I think I would rather replace the existing Power xformer rather than use a stepdown. would this be the best way to go?
Reading through some of the threads on this forum and some people place quite an importance on the power supply, so i guess the less clutter i.e stepdown etc, the better?
So help me here please with what should i get and why?

thanks C

 

[fdegrove]

XFORMER.

Hi,

Happy new Year to you too.

Your power xformer will need to be custom made for you I fear.
Check Maplin they may have something that comes close enough.

So,you will need a 240VAC primary.

On the secondary side I suggest:

For the heaters: 11.5 V @ 0.5A * 4 = 11.5VAC 2A

For the B+ 150VAC @ 3A.

The B+ may be on the high side so you may need to fit a higher value for R18.

It wouldn't hurt to up the value of the PSU filter caps for the B+ either.


Cheers,