Power Transformer

[TIMBO]

Hi guys, I'm looking at alternate power supplies and found this http://docs-asia.electrocomponents.com/webdocs/126e/0900766b8126ef7a.pdf

My idea is to run one 115v tap into a voltage tripler for the power tubes (6L6, EL34)and the other 115v into a doubler for PI and preamp.

I'm not up to speed on what the current draw will be but this transformer also comes in a 250va job as well. Thanks

[kagliostro]

Ciao TIMBO

The use of doubler and quadrupler is fine, only you must remember that a doubler gives 1/2 of the disposable current and a quadrupler 1/4

the tripler is an ugly beast, it has a bad effect on the transformer because it cause DC magnetization of the core

Instead, may be you can use it reversed, using the 115+115v output as an input and the official primary voltage abilities as a secondary

and also you can obtain different voltage connecting between official intakes

as an example, if you connect between the 575v and the 400v intakes, you have a 175v intake


Franco

[eleventeen]

There's generally no problem running a few preamp tubes pulling 1 mil each off a doubler. Usually there is no problem running an output section on a doubler, either.


But you may be disappointed with the performance of a tripler, meaning, unhappy with the behavior under load. Nevertheless, it's IMO a worthwhile learning experience to breadboard such a thing (leave your leads long!) to see if you can make it work. I'd urge you to breadboard such a thing (a tripler) and get some fat power resistors to simulate loading & see how it reacts to heavy load demand before committing to the design and thus the tranny.


I am not saying it's impossible. From my experience, a few things:


I call the caps inside the rectifier section "separator" caps. They maintain separation of the phases of the input signal and stack them up on top of each other. Because they are typically in series, their ufds get cut in half. Thus their charge-storage and smoothing capabilities are cut in half. Sometimes this cannot be overcome, even with fat caps on the rectifier output. I have found that one wants to place extra caps at the output of the rectifier section; and these, apart from increasing your parts costs, also start to take up real estate if your chassis is tight. Indeed, the caps inside the tripler are sometimes drawn on, current-wise, so much that even overly fat caps on the output can't overcome a bad ripple reaction under load. (though, maybe you like "sag")

[jjasilli]

I'm looking at alternate power supplies. . . a voltage tripler      WHY?

[TIMBO]

Hi guys, A bit more info on these K, I'm not sure that the taps are set up the way you have it drawn. The 175v is about what I am looking for. Thanks http://docs-asia.electrocomponents.com/webdocs/0120/0900766b80120ef6.pdf

[PRR]

> run one 115v tap into a voltage tripler ....the other 115v into a doubler

Really round-about.

There's no heater winding... you plan to cover that?

Get your little-tubes B+ from the big-tubes B+, like every sensible amp does. Little tubes need more filtering, and a large voltage drop helps with that.

A simple full wave bridge on the 0-208-600V connections gives DC Volts from 290V to 830v, dead-simple.

If you can find a 13-way (2-pole) 600V 1A power switch, you have elegant power-tapping to play a big amp in littler situations.

And you still have 115+115 primary in case you ever play the USA.

> not sure that the taps are set up the way you have

It is roughly like the attached. I am not sure of every number; you can check it when you get it.

> The 175v is about what I am looking for.

175V _AC_? The lowest full connections, stock, are 208V, and you need to parallel to get the full power rating.

Or 175V _DC_, which you will double and triple? 525V DC main tap is nothing special; use the 380V (31-38) connection to FWB for ~~520V DC, drop through 22K 2W and 40uFd to get 400V for driver, drop/filter again as needed for preampery.

[TIMBO]

Thanks PRR, This might be a lot of mucking around but the time and cost of getting a PT from US, I can get these local at $80.

The mystery amp I have has a huge PT that is better used in the MOODY build I am doing. This will service the mystery amp that will only have a pair of 6L6s/EL34 and three preamp tubes maybe a forth 
 

A 2A/12v transformer will handle the heaters.Thanks

[kagliostro]

I tried to do some math as to establish the voltage for each winding, but I had results which were a bit different from PRR's

However this doesn't really matter, what I want to say is that I didn't see a reason for which you can't use the intermediate winding connection as to obtain other voltage (different from stock connections)

Franco

[jazbo8]

Agree with PRR, get one that's designed for the purpose, check out Turner's PT for sale, the cheaper ones seem to fit the bill well - support your local vendors

[PRR]

> a reason for which you can't use the intermediate winding connection

If you don't use "ALL" the copper, you can not get full power.

The PT has 600V of winding.

Your sketch only uses 175V of that. You can only draw about 175/600 or 29% of the rated power.

Special case: there are two windings of 208/228. You may parallel these to get at least (2*208)/600 or 69% of power rating.

The ratings may be very conservative for Timbo's use. The transformer is for a control system which may be left on 24/7 for 20 years. (I suspect it is to run 120V/230V electronics around BIG motors and stuff which eats 480V or 600V power, where it may not be convenient to bring-in a 120/230 line, or the added low-volt wire and conduit would cost 10 times more than this transformer.)

Still I think you do not need voltage multipliers with this transformer.

[TIMBO]

Hey guys, Thanks for all the hard work. I have had success with a 70v transformer into a quadrupler with a B+ of about 390v, this transformer and caps about $60. With this transformer I was hoping to jag about 450v and at $80 its worth it. I can buy the real deal from the US for around $90 but shipping is another $40+. To get a 325-0-325 local is about $200 plus delivery. 

[kagliostro]

PRR you always bring me back to the right path

Many Thanks

---

TIMBO have you ever considered winding transformers by yourself

at DIYItalia we have a tread about this activity

and some guys have experimented with success the reuse of old scrap transformers as a source of supply for materials

give a look to the link which are present on this tread, may be you find something of your interest

http://www.diyitalia.eu/forum/viewtopic.php?f=22&t=9290

---

someone winds by hand

other use this

http://digilander.iol.it/giunchifabrizio/bobina.htm

or this simpler version 



Franco

[kagliostro]

Kudos to those suggesting wiring this iron so the secondaries become the primaries as this approach offers some huge options.

As PRR say

If you don't use "ALL" the copper, you can not get full power.

The PT has 600V of winding.

Your sketch only uses 175V of that. You can only draw about 175/600 or 29% of the rated power.

So to use in such a way a transformer you have and want to reuse may be an option, not the same if you have to buy the transformer

Here in Italy the situation isn't as in Australia, but also here we have PT and OT at a higher price that they would be, so isn't difficult to see italian guy looking for the reuse of transformers

Ciao

Franco

[sluckey]

JUST GET A TRANSFORMER THAT'S DESIGNED TO DO WHAT YOU WANT TO DO!

[TIMBO]

Again, thanks for it all the input, and I have to agree with Sluckey the right transformer for the right job. Thanks

[tubeswell]

or this simpler version 



Franco

'like'