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default
Guest

Tue Jul 30, 2019 9:45 pm   



On Tue, 30 Jul 2019 20:17:12 +0100, Peter Percival
<peterxpercival_at_hotmail.com> wrote:

Quote:
jurb6006_at_gmail.com wrote:
You can also use full wave WITH a center tap to get equal plus and minus voltages. Extra rectifiers mean shit -

https://www.digikey.com/product-detail/en/taiwan-semiconductor-corporation/SFF1604G-C0G/SFF1604GC0G-ND/7358615

$1.12 and that's two of them. See the specs ? Like 200V., 16A, 35nS.

Just how good of a rectifier do you need ?


What I need is a bridge (the transformer I'm considering doesn't has a
centre tapped secondary) that will handle 420 volts, 3.5 amps. Also,
I'd like recommendations for capacitor and inductor values for smoothing.


check out:
http://www.valvewizard.co.uk/smoothing.html

Very few amps use Pi filters these days (capacitor inductor capacitor)
that's more common back when capacitors were these huge metal cans
with aluminum foil paper and oil and had a rating of only ~1-10
microfarads. Today they use electrolytic caps with much higher
capacity and avoid the expense of big heavy inductors.

http://education.lenardaudio.com/en/14_valve_amps_6.html

Phil Allison
Guest

Tue Jul 30, 2019 10:45 pm   



Peter Percival wrote:
Quote:

What is the advantage of a four diode bridge full-wave rectifier over a
two diode full-wave rectifier. There must be some, else why accept the
extra cost?


** The extra cost accrues with the two diode rectifier - cos the larger, centre tapped transformer needed increases cost more than two more diodes do.

Two diode, full wave voltage doubler supplies are also common with direct off mains and transformer isolated supplies.

Two vacuum diode, full wave systems were once the norm but soon became obsolete when silicon diodes appeared in the 1960s.



..... Phil

Look165
Guest

Tue Jul 30, 2019 10:45 pm   



With a bridge, only 2 diodes on 4 work.
So it preserve diode life.

Peter Percival a écrit le 30/07/2019 à 16:04 :
Quote:
What is the advantage of a four diode bridge full-wave rectifier over
a two diode full-wave rectifier.  There must be some, else why accept
the extra cost?


Phil Allison
Guest

Tue Jul 30, 2019 11:45 pm   



Look165 is a Fucking Nut Case wrote:


> With a bridge, only 2 diodes on 4 work

** No, they all work.


Quote:
So it preserve diode life.


** False conclusion derived from a false assertion.

What do people here reckon this nutter is?

A Lebanese school boy?

A Chinese compewter geek ?

Escapee from an Indian mental asylum ?




...... Phil

whit3rd
Guest

Wed Jul 31, 2019 8:45 am   



On Tuesday, July 30, 2019 at 7:04:32 AM UTC-7, Peter Percival wrote:
Quote:
What is the advantage of a four diode bridge full-wave rectifier over a
two diode full-wave rectifier. There must be some, else why accept the
extra cost?


There's copper losses, and diode-drop losses, and core size difference.
For a center-tapped winding, you need longer wire for the coil, and
that raises the core size (unless you accept higher resistive heating
from thinner wire). With a full-wave bridge, four diodes, you have TWO
diode drops on each conducting half-cycle, but with a center-tapped two
diode fullwave rectified circuit, there's only ONE diode drop.

And, given a choice, a four-diode bridge and center-tapped coil gives you
TWO power supplies. That's very convenient.


Guest

Wed Jul 31, 2019 2:45 pm   



On Tuesday, July 30, 2019 at 3:26:29 PM UTC-5, Peter Percival wrote:
Quote:
jurb wrote:
You can also use full wave WITH a center tap to get equal plus and minus voltages. Extra rectifiers mean shit -

https://www.digikey.com/product-detail/en/taiwan-semiconductor-corporation/SFF1604G-C0G/SFF1604GC0G-ND/7358615

Two diodes sharing a cathode connection. Suppose one wants an
electrically identical pair of diodes but sharing the anode connection?

$1.12 and that's two of them. See the specs ? Like 200V., 16A, 35nS.

Just how good of a rectifier do you need ?


They got them, it is just a matter of learning how to use their selector pages. Problem is they changed them and while it all still works it seems you can't get back to "More Filters" and have to back out and reapproach.

They also have diodes in series in those packages.

You want to know about filtering ? Well you got 420 volts at 3.5 amps, that means pretty much a resistance of 120 ohms. Here comes the math, now if you are going brute force there is no inductor, just a ton of capacitance. Figure out how much ripple you can handle and get a cap big enough to not discharge more than that in 1/60th of a second.

That amount of ripple going into a choke will result in a certain voltage loss, which will be half the amplitude of the ripple. If you got 450 and 20 of ripple you got 440. that is what you'll get out of a choke. Into the next cap the whole thing is different because you have an impedance feeding that cap. The selection of the value of that next cap depends on the load and the variations in the load.

Too much inductance you lose all semblance of regulation, less inductance you need bigger caps.

If you have to much trouble figuring this out just adapt an extant design.


Guest

Wed Jul 31, 2019 2:45 pm   



Quote:
With a bridge, only 2 diodes on 4 work

** No, they all work.


You got him on semantics, he probably meant "conduct". Sure they are working when they are conducting, but they are also working when not conducting. They are blocking. When they no longer block they are considered not working.

Quote:
So it preserve diode life.


** False conclusion derived from a false assertion.


Also ignores some logic on the subject. I won't be as mean as you but I will say it - ijiot ! YOU pick the diodes, they don't pick you ! And do you care if the diode is 50 cents or 60 cents ?

I'm surprised I am even here. I did need a bit of a break though. Got any idea why the hell this Carver Receiver (MX-130) turns off the tuner when I turn off the speakers ? I decided to get away from it, and now I think I have a clue, it switches by relay, maybe somehow the 12 volt line is getting shorted... I'm just here to take a break from it.

But thing is, I gotta write a book or something. These component values and all that, people give way too much attention to that.

Peter Percival
Guest

Wed Jul 31, 2019 3:45 pm   



jurb6006_at_gmail.com wrote:
Quote:
On Tuesday, July 30, 2019 at 3:26:29 PM UTC-5, Peter Percival wrote:
jurb wrote:
You can also use full wave WITH a center tap to get equal plus and minus voltages. Extra rectifiers mean shit -

https://www.digikey.com/product-detail/en/taiwan-semiconductor-corporation/SFF1604G-C0G/SFF1604GC0G-ND/7358615

Two diodes sharing a cathode connection. Suppose one wants an
electrically identical pair of diodes but sharing the anode connection?

$1.12 and that's two of them. See the specs ? Like 200V., 16A, 35nS.

Just how good of a rectifier do you need ?


They got them, it is just a matter of learning how to use their selector pages. Problem is they changed them and while it all still works it seems you can't get back to "More Filters" and have to back out and reapproach.

They also have diodes in series in those packages.

You want to know about filtering ? Well you got 420 volts at 3.5 amps, that means pretty much a resistance of 120 ohms. Here comes the math, now if you are going brute force there is no inductor, just a ton of capacitance. Figure out how much ripple you can handle and get a cap big enough to not discharge more than that in 1/60th of a second.

That amount of ripple going into a choke will result in a certain voltage loss, which will be half the amplitude of the ripple. If you got 450 and 20 of ripple you got 440. that is what you'll get out of a choke. Into the next cap the whole thing is different because you have an impedance feeding that cap. The selection of the value of that next cap depends on the load and the variations in the load.

Too much inductance you lose all semblance of regulation, less inductance you need bigger caps.

If you have to much trouble figuring this out just adapt an extant design.


Please direct me to one ad tell me how to adapt it.

>

Phil Allison
Guest

Thu Aug 01, 2019 12:45 am   



jurb = jerkoff fool @gmail.com wrote:


Quote:
With a bridge, only 2 diodes on 4 work

** No, they all work.

You got him on semantics, he probably meant "conduct". Sure they are working when they are conducting, but they are also working when not conducting. They are blocking. When they no longer block they are considered not working.



** All four diodes conduct - half of them during each half cycle.

With two diode, full wave rectifiers its one diode per half cycle.

The claim about extending diode life was bullshit

Just like every single claim YOU post.



...... Phil

Look165
Guest

Thu Aug 01, 2019 9:45 am   



I was meaning that at half wave, only 2 diodes work.
For exemple : D1-D3 for +half wave, D2-D4 for -half wave.
In 2 diodes rectifier, the 2 always work.

Phil Allison a écrit le 01/08/2019 à 01:20 :
Quote:
jurb = jerkoff fool @gmail.com wrote:


With a bridge, only 2 diodes on 4 work
** No, they all work.
You got him on semantics, he probably meant "conduct". Sure they are working when they are conducting, but they are also working when not conducting. They are blocking. When they no longer block they are considered not working.


** All four diodes conduct - half of them during each half cycle.

With two diode, full wave rectifiers its one diode per half cycle.

The claim about extending diode life was bullshit

Just like every single claim YOU post.



..... Phil




default
Guest

Thu Aug 01, 2019 3:45 pm   



On Wed, 31 Jul 2019 06:26:17 -0700 (PDT), jurb6006_at_gmail.com wrote:

Quote:
With a bridge, only 2 diodes on 4 work

** No, they all work.

You got him on semantics, he probably meant "conduct". Sure they are working when they are conducting, but they are also working when not conducting. They are blocking. When they no longer block they are considered not working.

So it preserve diode life.


** False conclusion derived from a false assertion.

Also ignores some logic on the subject. I won't be as mean as you but I will say it - ijiot ! YOU pick the diodes, they don't pick you ! And do you care if the diode is 50 cents or 60 cents ?

I'm surprised I am even here. I did need a bit of a break though. Got any idea why the hell this Carver Receiver (MX-130) turns off the tuner when I turn off the speakers ? I decided to get away from it, and now I think I have a clue, it switches by relay, maybe somehow the 12 volt line is getting shorted... I'm just here to take a break from it.


I had a computer that would reset when I turned off the amplified
speakers before turning off the computer. A small common mode filter
on the amp cured the problem.
Quote:

But thing is, I gotta write a book or something. These component values and all that, people give way too much attention to that.


Ya think? Generally speaking, they are damn serious when they talk
about "absolute maximum values.."

And when they specify a mosfet (for instance) at a current capacity
that would cause its leads to melt, or unsolder itself from the board
- well then they are lying.

Look165
Guest

Thu Aug 01, 2019 3:45 pm   



Being French, I don't know the exact way you think !

default a écrit le 01/08/2019 à 16:24 :
Quote:
On Wed, 31 Jul 2019 06:26:17 -0700 (PDT), jurb6006_at_gmail.com wrote:

With a bridge, only 2 diodes on 4 work
** No, they all work.
You got him on semantics, he probably meant "conduct". Sure they are working when they are conducting, but they are also working when not conducting. They are blocking. When they no longer block they are considered not working.

So it preserve diode life.

** False conclusion derived from a false assertion.
Also ignores some logic on the subject. I won't be as mean as you but I will say it - ijiot ! YOU pick the diodes, they don't pick you ! And do you care if the diode is 50 cents or 60 cents ?

I'm surprised I am even here. I did need a bit of a break though. Got any idea why the hell this Carver Receiver (MX-130) turns off the tuner when I turn off the speakers ? I decided to get away from it, and now I think I have a clue, it switches by relay, maybe somehow the 12 volt line is getting shorted... I'm just here to take a break from it.
I had a computer that would reset when I turned off the amplified
speakers before turning off the computer. A small common mode filter
on the amp cured the problem.
But thing is, I gotta write a book or something. These component values and all that, people give way too much attention to that.
Ya think? Generally speaking, they are damn serious when they talk
about "absolute maximum values.."

And when they specify a mosfet (for instance) at a current capacity
that would cause its leads to melt, or unsolder itself from the board
- well then they are lying.


Bob Engelhardt
Guest

Thu Aug 01, 2019 5:45 pm   



On 8/1/2019 10:24 AM, default wrote:
....
Quote:
And when they specify a mosfet (for instance) at a current capacity
that would cause its leads to melt, or unsolder itself from the board
- well then they are lying.


You think? I happen to stumble across a MOSFET in a TO-227 that was
spec'ed for 300A & 1500W. How is that useful? Shouldn't they also say
that it requires a LN2-cooled heatsink? And if you do need, say, a 15A
MOSFET, how do you find it, what with all the bogus spec's?

Phil Allison
Guest

Thu Aug 01, 2019 10:45 pm   



Look165 is a Mad Frog wrote:

DO NOT TOP POST !!!!!

It pisses usenet readers off !!


Quote:
I was meaning that at half wave, only 2 diodes work.
For exemple : D1-D3 for +half wave, D2-D4 for -half wave.
In 2 diodes rectifier, the 2 always work.



** No they do not !!!

It's one diode at a time, like I already posted.

Please go away you tedious wog fool.



..... Phil

John Larkin
Guest

Sat Aug 03, 2019 9:45 pm   



On Thu, 01 Aug 2019 10:24:28 -0400, default <default_at_defaulter.net>
wrote:

Quote:
On Wed, 31 Jul 2019 06:26:17 -0700 (PDT), jurb6006_at_gmail.com wrote:

With a bridge, only 2 diodes on 4 work

** No, they all work.

You got him on semantics, he probably meant "conduct". Sure they are working when they are conducting, but they are also working when not conducting. They are blocking. When they no longer block they are considered not working.

So it preserve diode life.


** False conclusion derived from a false assertion.

Also ignores some logic on the subject. I won't be as mean as you but I will say it - ijiot ! YOU pick the diodes, they don't pick you ! And do you care if the diode is 50 cents or 60 cents ?

I'm surprised I am even here. I did need a bit of a break though. Got any idea why the hell this Carver Receiver (MX-130) turns off the tuner when I turn off the speakers ? I decided to get away from it, and now I think I have a clue, it switches by relay, maybe somehow the 12 volt line is getting shorted... I'm just here to take a break from it.

I had a computer that would reset when I turned off the amplified
speakers before turning off the computer. A small common mode filter
on the amp cured the problem.

But thing is, I gotta write a book or something. These component values and all that, people give way too much attention to that.

Ya think? Generally speaking, they are damn serious when they talk
about "absolute maximum values.."

And when they specify a mosfet (for instance) at a current capacity
that would cause its leads to melt, or unsolder itself from the board
- well then they are lying.


It's interesting to test parts to see how much margin there is from
the data sheet. Numbers like 5:1 are common. Ceramic capacitors can be
over 20:1.

I use "abs max 2 volt reverse" schottky diodes at -5, and 7 volt max
PHEMTS at 15.

A 12 volt max LM1117 regulator fails at about 60. Most mosfet gates
blow out around 70.

On the other hand, many mosfet power ratings are absurd fantasies. IR
pioneered lying about that, and everyone else had to go along.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

That Ohmite resistor is rated for 45 watts.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

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