Questions about doubler - triplers - quadruplers and so on ......... ???

[kagliostro]

Which are the differences about a B+ obtained via a standard bridge with condenser

and B+ obtained via doubler - triplers .................

naturally the consumption seen from the transformer is duplicate, tripled and so on

but which other differences ? different ripple ............. different frequency of ripple ?


and also


with SS bridge and condenser the assumption is to multiply for 1.4 so AC100v * 1.4 = DC140v

but what happen if is used a doubler, a tripler, a quadrupler ?

AC100v * 2 = DC200v

AC100v * 3 = DC300v

or instead it is

AC100v * 2 = DC240v

AC100v * 3 = DC340v

Very confused about the math is back to this way of rectify 

Kagliostro

[RicharD]

http://www.play-hookey.com/ac_theory/ps_v_multipliers.html

A doubler for all intents and purposes:  Vout = 2Vpeak-(voltage drop of the diodes)  Of course you may need to factor in some loading drop too.  Have you played with Duncan's PSU Designer 2?  It has a doubler circuit but no tripler.  Doublers are cool but get wonky fast under higher current conditions.  For example if you ave a 25V 20mA transformer, you should be able to get 49VDC at 10mA using a doubler constructed from 1N4007's but if you're really demanding 10mA, you're gonna have additional sag.  Yeah we like sag in guitar amps up to a point.  It's probably safe to assume that doublers double the sag too.  IMO, triplers and beyond should be avoided 99 times out of 100.  Suppose you needed 300V @ 100mA.  Your PT would be 100V @ 300mA.  It's like trying to seesaw with a fat man.

[moody]

http://www.play-hookey.com/ac_theory/ps_v_multipliers.html

A doubler for all intents and purposes:  Vout = 2Vpeak-(voltage drop of the diodes)  Of course you may need to factor in some loading drop too.  Have you played with Duncan's PSU Designer 2?  It has a doubler circuit but no tripler.  Doublers are cool but get wonky fast under higher current conditions.  For example if you ave a 25V 20mA transformer, you should be able to get 49VDC at 10mA using a doubler constructed from 1N4007's but if you're really demanding 10mA, you're gonna have additional sag.  Yeah we like sag in guitar amps up to a point.  It's probably safe to assume that doublers double the sag too.  IMO, triplers and beyond should be avoided 99 times out of 100.  Suppose you needed 300V @ 100mA.  Your PT would be 100V @ 300mA.  It's like trying to seesaw with a fat man.

The doubler is a combination of doubling / smoothing and full wave bridge.  Therefore it is double the voltage x 1.4 and then add sag.

I've quite a bit of experience with quadruplers.  From experience, a measured 68volts through a quadrupler should be 381ish.  In reality it is closer to 360 volts.  When run near the edge there is significant sag which approaches the sag you would get from a valve rectifier.

At the same time, the current is divided by the level of doubling and divided by 1.4.  So if you needed 100ma through a quadrupler then you would need 560ma to begin with.

[darryl]

I have used voltage multipliers in many amplifier builds without problems, most recently in a set of four amplifiers I called the "holiday family". Details of the first in the series are here: http://www.guitargear.net.au/discussion/index.php?topic=26388.0

The power supply used in these amplifiers was a voltage quadrupler:



The following calculations will be rounded to sensible levels of accuracy, and will ignore effects such as diode voltage drops and transformer regulation.

The power transformer is 56VAC @ 2.4A.

So in a quadrupler, the output voltage is 56 * 1.4 * 4 = 314 volts DC.

The available output current is 2.4 / 1.4 = 1.7  Then 1.7 / 4 = 0.425  or about 420mA.

Actual B+ voltages measured in the amplifier mentioned above were:

1. At turn-on with cold valves:           334
2. Quiescent - valves warm:              319
3. At maximum sine-wave output:       315
4. At max clipping - i.e. square wave:  311

So the theoretical figure matched the observed results fairly well.

[kagliostro]

MANY THANKS Butterylicious - Moody - Darryl

about math and real world test I think I've understand

but what about noise & Co. ?

In my mind a simply SS rectify gives ripple at the same frequency of the AC Line - 50Hz here in Italy

but which is the ripple frequency using a doubler or quadrupler ?

the 50Hz will rise to 100Hz and 200Hz ?

this higher frequency ripple isn't more difficult to be eliminated than a lower frequency ripple ?

Are these only my conjectures ? 

Thanks

Kagliostro

[moody]

I have used voltage multipliers in many amplifier builds without problems, most recently in a set of four amplifiers I called the "holiday family". Details of the first in the series are here: http://www.guitargear.net.au/discussion/index.php?topic=26388.0

The power supply used in these amplifiers was a voltage quadrupler:



The following calculations will be rounded to sensible levels of accuracy, and will ignore effects such as diode voltage drops and transformer regulation.

The power transformer is 56VAC @ 2.4A.

So in a quadrupler, the output voltage is 56 * 1.4 * 4 = 314 volts DC.

The available output current is 2.4 / 1.4 = 1.7  Then 1.7 / 4 = 0.425  or about 420mA.

Actual B+ voltages measured in the amplifier mentioned above were:

1. At turn-on with cold valves:           334
2. Quiescent - valves warm:              319
3. At maximum sine-wave output:       315
4. At max clipping - i.e. square wave:  311

So the theoretical figure matched the observed results fairly well.

Darryl, may I ask what the measured voltage of the 56 volt transformer is when actually plugged in?  I have noticed that many of the 30v transformers for example are in real life 34 or 35 volt even when wall voltage is very close to 240 volt exactly?

[Merlin]

but which is the ripple frequency using a doubler or quadrupler ?

There are different kinds of voltage multiplier.
Some are half-wave, so the ripple will be 50Hz.
Some are full-wave, so the ripple will be 100Hz.

However, there are some multiplier circuits that are combinations of full-wave and half-wave, so you can get asymmetrical ripple which is both 50Hz and 100Hz!

I devoted a chapter to voltage multipliers in my book.
http://www.freewebs.com/valvewizard2/book2.html

{EDIT -- untangled "/quote" -- PRR}

[kagliostro]

MANY THANKS Merlin

There are different kinds of voltage multiplier.
Some are half-wave, so the ripple will be 50Hz.
Some are full-wave, so the ripple will be 100Hz.

However, there are some multiplier circuits that are combinations of full-wave and half-wave, so you can get asymmetrical ripple which is both 50Hz and 100Hz!

That is OK


-------------


I devoted a chapter to voltage multipliers in my book.

That of my order for your second book was becoming a "Never End Story"

I ordered it to my supplier the 18/12/2010

here:

http://www.libreriauniversitaria.it/c_power_search.php?shelf=BEN&q=merlin+Blencowe&submit=


the 14/01/2011 they sent me a message : "the book at the moment is not momentarily available from our suppliers"

the 14/01/2011 I reordered the book, hoping it will be soon available

the 17/01/2011 I received another message: "the book you previously ordered is now available"

today (20/01/2011) if I look to my order I read: Open, but not delivered  

Really I'm waiting to read that book, but it seems I must wait some other time ..............

Kagliostro

[kagliostro]

Today I got the new Merlin's PS Book     

I think I've something to read for the next days

Kagliostro

[Willabe]

kagliostro,

Hey, you got it.          One of these days I've got to get around to ordering that book too.     



      Brad