Power Supply Rectification and Smoothing

[Eeyore]

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers, and has called those who differ from his advice to be either
IDIOTS, or to be taken out and SHOT.

That's because they gave very BAD or incompetent advice.

So you say, but then YOU have said that the motor speed controllers
are as robust as motors wrt current requirements

Where did I say that ? Those aren't my words for sure.

You seem to be quick to draw possibly flawed conclusions from a limited understanding
of what you're being told.

Graham

 

[Eeyore]

spamfree@spam.heaven wrote:

that the guy (familiar with the speed controllers that you apparently are not) is
a grade one
IDIOT for calculating the required smoothing capacitance for a lesser
ripple than you

Anyone suggesting that a THREE FARAD smoothing cap is suitable for this application
is a MENTAL DEFECTIVE, for multiple reasons it would clearly be a waste of time to
attempt to explain to your gullible and addled brain.

Sorry that I was too polite to make that clearer earlier

I'm sorry but it seems your limited understanding of technology makes you far too
willing to believe the IDIOTS. Clearly I'm wasting my time. Get a damn education
before criticising me next time will you ?

Have fun with the IDIOT ideas won't you ?

Graham

 

[Eeyore]

spamfree@spam.heaven wrote:

Sorry, but perhaps your arrogance has given me this
impression.

Your gullibility has convinced me you're another grade one IDIOT in the making.

If you could only be bothered to learn some electronics ! That's how I learnt stuff.
By ** STUDY **.

Jesus wept ! And you clowns are the future ?

Graham

 

On Wed, 17 Oct 2007 11:20:14 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers

What 'clangers' ?

Aww, let's see...

-Motor speed controller just the same as motor wrt current input,
-500W motor is 500W IN according to IEC.
-The guy who calculated the ripple capacitance for the current
requirements for the controllers he is familiar with was a grade one
IDIOT.

Should I go on? These make me take anything you say with a grain of
salt. Can't you see that? I'll let someone else with more temperate
language and proven wisdom confirm or refute anything that you advise.
(Although, anyone with any wisdom would likely have the wisdom not to
get involved with anyone so acquainted with the hyperbolic outburst)

jack

 

On Wed, 17 Oct 2007 11:38:34 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

On Wed, 17 Oct 2007 07:56:41 GMT, Ross Herbert
rherber1@bigpond.net.au> wrote:

What you don't seem to understand is that the amplitude of a mains
spike will be reduced by the turns ratio of the transformer at the
secondary. In your case about 6.5 times reduction.

But let's see, its energy content will remain about the same,

Well actually NO. Ross explained how the transformer will tend to attenuate and
filter it.

Yes, I got that useful piece of information and acknowledged it,
thankyou.

and according to most experts in this area that I've read, electrolytic
cap life is reduced by spikes, especially when the rated voltage is so
close to the actual working voltage. (50V caps for a 36V supply)

That's NOT close. Those 50V caps have a 63V 'surge' rating and you're not
remotely near either of those ratings. Why do you think a surge rating is
specified ?

Is it? Who said? I said that some similar caps at 6 times the price
had a 63V surge rating. I only know that the 75c caps have a 50V
rating. But look, you are getting hot under the collar about a minor
point in my quest for info about design of my PS.

If you could use 100V caps or 50V caps for this application at the
same price, which would you choose, and why?

Now I'm a total electronics newbie, so please don't jump on me for
this question, but what could happen (worst case) when I switch on the
240V mains soon after switching it off, and the transfromer core is
still magnetised, and the mains phase angle at switch-on is in the
position to make it go "boing!!!" ? jack

 

On Wed, 17 Oct 2007 11:39:55 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

my secondary windings are way more robust than delicate electrolytic caps

Large power supply electrolytics are NOT 'delicate'.

Are these large power supply electrolytics?

The similar but 6x priced ones are:
22mm diameter and 40mm high.
have a ripple current spec of 2.34A
have a temp rating of 105C

There is a larger PS cap nearby that is 51mm diam and 83mm high
It is 8200uF and 100V rated with a 5.8A ripple spec
It is 45 times the price of my preferred caps.

I hope the cheapies are the same spec as the 6x beasties.

BTW, aren't electrolytic caps way more delicate than either motors or
30A transformer windings. jack

 

On Wed, 17 Oct 2007 11:43:34 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

My main problem of ignorance (I've plenty of these now is how
smooth a current these motor speed controllers demand.

The controllers won't 'demand' ANYTHING.

That's a figure of speech here, Graham. It means "require".

They'll just pass the voltage/current.

OK. I take your opinion on board.

You did say they were PWM types, yes ?

Yes

All they do is switch the circuit on and
off at a high speed.

Yes, so I believe. And the control of the frequency of this switching
is critical to the speed control function of the thing. Perhaps ripple
might upset this control?

They simply 'don't care' about the voltage you supply as
long as it's not above their specified rating.

And you apparently don't know that they cut out if the input drops
below 31.5V. That's half a volt above the residual ripple you
calculated for. Perhaps you owe the guy who you classed as a grade one
IDIOT an apology?

The only think that might happen IME is that your motor might hum audibly very
slightly due to supply ripple.

And perhaps have flaky speed control? Or cut out every so often?
Hum I like in a lathe


jack

 

On Wed, 17 Oct 2007 11:19:13 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
Eeyore wrote:

Such transients won't appreciably affect the voltage on the reservoir caps, there
isn't enough energy in
them to do so.

Surely that depends on how much energy is in the mains transients.
With a rated surge tolerance of less than twice the nominal working
voltage.... Careful Laddie, ye'll get a bullet!

I suggest you take a look at the voltage on some reservoir caps with a scope and look
for these alleged transients that over-volt them. You'll be looking a long time.

OK, I will one day. But can you see my dilemma? I see you use
intemperate language and assert errors, so how can I take notice of
what you say here?

I have given a worked (mathematical) example of the effect of a transient.

I asked if this was based on the max spike I would likely suffer.
And then I want to know what effect on lifespan these spikes might
have on 50V cap in a 36V PS. If <5% OK, otherwise...

Science beats voodoo, myth and rumour (and cookbook equations) in my book.

Of course, but you give that label to everything but your opinion, and
your opinions include several glaring errors so far.
Your opinion of the ripple tolerance of DC brushed motor speed
controllers is worth nothing to me, sorry, and that is the main query
I have posed here

YOU may know what you know, and what the status is
of what you say, but I'm afraid that I can't tell. jack

I can though. I've just about had my fill of IDIOTS and trust me they're everywhere these
days, screwing things up wherever they go.

And even you, the self-proclaimed expert of experts have shown
yourself to be an IDIOT here.

Many even rise to quite high levels of management where they can cause untold damage.
http://en.wikipedia.org/wiki/Peter_Principle

Only the very gullible are in danger on usenet.
And gullible I ain't.
I've a very sensitive bullshit detector hated buy not a few on usenet
over the years

ps My problem with your advice is that it seems so black-and-white
and adamant. From my reading of the EvoxRifa article, it seems that
capacitor life is the key factor. The electrolytics in some of my
catalogues are rated at ~2000 hours.

2000 hours AT THE RATED AMBIENT TEMPERATURE and the RATED RIPPLE CURRENT.

I've never seen ambient temp rated. Perhaps I need to get out more.
I've only seen max temp rated.

Voltage
incidentally is the one thing that appears to have NO influence on lifetime provided it's
within the rated value.

Could well be true. But as the person telling me has lost his
credibility...

So a 37V rated cap would last as long as a 100V rated cap, so long as
36V was never exceeded? What is the margin of error here?
20% +/- on capacitance, usually.

Life doubles typically for every 10C below that figure. Operate '2000 hour' 85C rated
electrolytics at 45C ambient and they'll be good for 32,000 hours.

Sorry, I don't follow. Where I live, 45C is the record high ambient
outside on a hot Summer day. Where do they have 85C ambient temps?

You need to read that Evox article in more detail perhaps and/or place it in the context
of other information it doesn't provide before drawing conclusions like those you have.

Not sure of what conclusions you are referring to. I've asked
questions, and quoted it, but...

Evox Rifa seem to be saying that
spikes and transients (yes, from the mains) can shorten cap life.

If those transients EXCEED the voltage rating. Which they won't in this case.

Taken on board, thankyou.

If you are saying that this is not significant in the case

No, I'm saying that those transients will have minimal effect on the voltage on the
reservoir caps. A more detailed explanation of this has been supplied by Ross Herbert.

But my interest here is in cap lifespan. If this is not affected, I
don't care what the transients do.

I'm citing here, then that's fine, but to scream that anyone who states the
principle, or who disagrees with your proclamations is a grade one
IDIOT, or should be SHOT shows your advice is flaky at best.

My advice is first class actually.

In the light of your clangers listed elsewhere? I don't theenk so!

Of course if you were to do some serious study, you'd
understand that.

Well, I studied what the IEC said on motor power and found you were
dead wrong, I studied many anecdotes of motor and controller failure,
and found you were wrong...

The thing about the IDIOTS is that they can sound plausible too to the
newbie or non-expert. And there's no shortage of them. The only way to remove the
influence of their stupidity is to reveal them for what they are.

How apt. jack

 

On Wed, 17 Oct 2007 14:27:09 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers, and has called those who differ from his advice to be either
IDIOTS, or to be taken out and SHOT.

That's because they gave very BAD or incompetent advice.

So you say, but then YOU have said that the motor speed controllers
are as robust as motors wrt current requirements

Where did I say that ? Those aren't my words for sure.

You seem to be quick to draw possibly flawed conclusions from a limited understanding
of what you're being told.

I wrote:
I still can't find out what the smoothness requirements are for these
Chinese scooter motor controllers.

You wrote:
Very little I expect. It's just a motor.

I wrote:
And a PWM speed controller.

You wrote:
So ? They'll work just fine with a bit of ripple too. You're fretting
over things of no consequence.

jack

 

On Wed, 17 Oct 2007 14:32:03 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

that the guy (familiar with the speed controllers that you apparently are not) is
a grade one
IDIOT for calculating the required smoothing capacitance for a lesser
ripple than you

Anyone suggesting that a THREE FARAD smoothing cap is suitable for this application
is a MENTAL DEFECTIVE, for multiple reasons it would clearly be a waste of time to
attempt to explain to your gullible and addled brain.

Code for "you can't"? Snaaaaarfff

And to refresh your less than perfect memory, the guy did not say a 3F
cap was suitable. That's your heated imagination at work. He said that
to do what I needed would require a 3F cap - a very large expensive
thing. He suggested a totally different construction to produce the
required 36VDC

Sorry that I was too polite to make that clearer earlier

So what happened to this politeness when you failed to acknowledge
that you were just a dead wrong smartarse when you claimed arrogantly
that the IEC standard was for motor power to be INPUT power?

I'm sorry but it seems your limited understanding of technology makes you far too
willing to believe the IDIOTS.

Can you show one example of this?
I don't believe YOU, as you have shown yourself to be an IDIOT.
That's progress, surely.

Clearly I'm wasting my time.

Well we wouldn't want you to waste time owning your clangers here,
would we?

Get a damn education.

I'm trying, but I'm damned sure I won't take notice of proven IDIOTS
like you, thanks.

before criticising me next time will you ?

Well, you make finding fault with your intemperate language and
blindingly arrogant errors so easy.

Have fun with the IDIOT ideas won't you ?

Isn't that just the way, with your idiots! To spread errors and
misinformation and then chuck a hissy fit when called, and claim
everyone else is an idiot?

jack

 

[Eeyore]

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers

What 'clangers' ?

Aww, let's see...

-Motor speed controller just the same as motor wrt current input,
-500W motor is 500W IN according to IEC.
-The guy who calculated the ripple capacitance for the current
requirements for the controllers he is familiar with was a grade one
IDIOT.

Should I go on? These make me take anything you say with a grain of
salt. Can't you see that? I'll let someone else with more temperate
language and proven wisdom confirm or refute anything that you advise.
(Although, anyone with any wisdom would likely have the wisdom not to
get involved with anyone so acquainted with the hyperbolic outburst)

I take it you haven't been able to work out how STUPID the idea of 3 FARADS of
psu capacitance is yet?

If you're not capable of understanding that, you're a waste of time.

Graham

 

On Wed, 17 Oct 2007 14:34:23 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

Sorry, but perhaps your arrogance has given me this
impression.

Your gullibility has convinced me you're another grade one IDIOT in the making.

If you could only be bothered to learn some electronics ! That's how I learnt stuff.
By ** STUDY **.

Jesus wept ! And you clowns are the future ?

Not much of it [future], I'm afraid, I'm in my mid 60s and trying to
learn a new area. Your tutelage has been proven to be flaky. First
with your list of patent errors, and now with your desperate ploy of
abusing those who try to call you on them. jack

ps wouldn't it be neater to admit your errors, learn and move on?
I am happy to acknowledge any errors I make in any of the other areas
where I would claim a modicum of expertise. This way, I learn, and
it's much nicer when others don't regard you as an arrogant
bullshitartist. DAMHIKT

 

On Wed, 17 Oct 2007 15:09:18 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers

What 'clangers' ?

Aww, let's see...

-Motor speed controller just the same as motor wrt current input,
-500W motor is 500W IN according to IEC.
-The guy who calculated the ripple capacitance for the current
requirements for the controllers he is familiar with was a grade one
IDIOT.

Should I go on? These make me take anything you say with a grain of
salt. Can't you see that? I'll let someone else with more temperate
language and proven wisdom confirm or refute anything that you advise.
(Although, anyone with any wisdom would likely have the wisdom not to
get involved with anyone so acquainted with the hyperbolic outburst)

I take it you haven't been able to work out how STUPID the idea of 3 FARADS of
psu capacitance is yet?

I didn't need to. The guy who calculated the value dismissed it and
showed me another way to get my smooth 36VDC.

If you're not capable of understanding that, you're a waste of time.

See above. How about your precious IEC? and the depicable NEMA?

Snaarrrffff!!!

jack

 

[Eeyore]

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
Eeyore wrote:
spamfree@spam.heaven wrote:
me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers, and has called those who differ from his advice to be either
IDIOTS, or to be taken out and SHOT.

That's because they gave very BAD or incompetent advice.

So you say, but then YOU have said that the motor speed controllers
are as robust as motors wrt current requirements

Where did I say that ? Those aren't my words for sure.

You seem to be quick to draw possibly flawed conclusions from a limited understanding
of what you're being told.

I wrote:
I still can't find out what the smoothness requirements are for these
Chinese scooter motor controllers.

You wrote:
Very little I expect. It's just a motor.

I wrote:
And a PWM speed controller.

You wrote:
So ? They'll work just fine with a bit of ripple too. You're fretting
over things of no consequence.

See, I said nothing about 'robustness'. That's an entirely different matter and won't be
affected by supply ripple.

Graham

 

[Eeyore]

spamfree@spam.heaven wrote:

If you could use 100V caps or 50V caps for this application at the
same price, which would you choose, and why?

50V because they would be smaller and lighter. For any givens series of capacitors
from a given vendor, size is determined by the combintion of Capacitance and Voltage
rating, the so-called 'CV product'. 100V caps would be twice as large and have no
benefit. They would of course for this very reason be more costly, so your idea that
they could be the same price falls at the first hurdle.

Graham

 

[Eeyore]

spamfree@spam.heaven wrote:

Eeyore wrote:

spamfree@spam.heaven wrote:

My main problem of ignorance (I've plenty of these now is how
smooth a current these motor speed controllers demand.

The controllers won't 'demand' ANYTHING.

That's a figure of speech here, Graham. It means "require".

They don't REQUIRE anything like 'smooth current' (actually you mean VOLTAGE)
either !

You have some very woolly deas.

Graham

 

[Eeyore]

spamfree@spam.heaven wrote:

Eeyore wrote:

You did say they were PWM types, yes ?

Yes

All they do is switch the circuit on and
off at a high speed.

Yes, so I believe. And the control of the frequency of this switching
is critical to the speed control function of the thing. Perhaps ripple
might upset this control?

NO.

They simply 'don't care' about the voltage you supply as
long as it's not above their specified rating.

And you apparently don't know that they cut out if the input drops
below 31.5V.

Since it's the first time you've mentioned it ............

That's half a volt above the residual ripple you
calculated for. Perhaps you owe the guy who you classed as a grade one
IDIOT an apology?

3 FARAD caps aren't going to solve that one. It's still a stupid idea.

Furthermore, ripple is only one reason the supply voltage drops. You'll also get
good old-fashioned resistive loading of the circuit which'll cause the voltage to
droop.

If there's an undervoltage cut-out at 31.5V and the suggested operational voltage
is 36V then I'll wager it's actually designed to run from 3 x 12V lead acid
batteries which have a 'true' voltage more like 12.6V. So, look at furnishing a
37.2 volt (or higher) supply when off-load.

Graham

 

[Eeyore]

spamfree@spam.heaven wrote:

On Wed, 17 Oct 2007 14:32:03 +0100, Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

that the guy (familiar with the speed controllers that you apparently are not) is
a grade one
IDIOT for calculating the required smoothing capacitance for a lesser
ripple than you

Anyone suggesting that a THREE FARAD smoothing cap is suitable for this application
is a MENTAL DEFECTIVE, for multiple reasons it would clearly be a waste of time to
attempt to explain to your gullible and addled brain.

Code for "you can't"? Snaaaaarfff

Your snide and uneducated remarks in support of utter IDIOTS are getting tiring. I've
wasted more than enough time on you now.

Ever heard of the phrase 'pearls before swine' ?

Graham

 

On Wed, 17 Oct 2007 16:51:40 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

Eeyore wrote:
spamfree@spam.heaven wrote:
Eeyore wrote:
spamfree@spam.heaven wrote:
me <me@here.net> wrote:

You have been given good advice, if you don't like it then don't use it.

Good advice from whom? I've had different advice from different
so-called experts, and one of these has patently stated several
clangers, and has called those who differ from his advice to be either
IDIOTS, or to be taken out and SHOT.

That's because they gave very BAD or incompetent advice.

So you say, but then YOU have said that the motor speed controllers
are as robust as motors wrt current requirements

Where did I say that ? Those aren't my words for sure.

You seem to be quick to draw possibly flawed conclusions from a limited understanding
of what you're being told.

I wrote:
I still can't find out what the smoothness requirements are for these
Chinese scooter motor controllers.

You wrote:
Very little I expect. It's just a motor.

I wrote:
And a PWM speed controller.

You wrote:
So ? They'll work just fine with a bit of ripple too. You're fretting
over things of no consequence.

See, I said nothing about 'robustness'. That's an entirely different matter and won't be
affected by supply ripple.

Can't you understand plain English?
Robustness in this context is the ability (strength) to withstand
ripple. A quality you claimed for both controller and motor, despite
your patent ignorance of the former.

Sheesh, are you a politician in election mode?

jack

 

On Wed, 17 Oct 2007 17:13:47 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

spamfree@spam.heaven wrote:

If you could use 100V caps or 50V caps for this application at the
same price, which would you choose, and why?

50V because they would be smaller and lighter. For any givens series of capacitors
from a given vendor, size is determined by the combintion of Capacitance and Voltage
rating, the so-called 'CV product'. 100V caps would be twice as large and have no
benefit. They would of course for this very reason be more costly, so your idea that
they could be the same price falls at the first hurdle.

They would last exactly the same lifespan?

The price is merely what they are offered for.
If I had the choice of 100V caps at 75c compared with 50V caps for
$4.95, the prices from the vendors I have access to here, I would
choose the 100 V. Size and weight is of no consequence in my
application. Now I really am not sure whether the 100V mothers will
last 1 second more than the 50V in this application, but I sure as
hell can't trust your advice. Sorry, jack