Meat Plow wrote:
On Tue, 01 Jan 2008 12:28:22 +0000, mike wrote:

Meat Plow wrote:
On Tue, 01 Jan 2008 04:40:35 +0000, mike wrote:

Meat Plow wrote:
On Mon, 31 Dec 2007 21:27:39 -0500, mm wrote:

It seems I mailed home the powersupply cord and transformer for my IBM
ThinkPad 600E, instead of putting it in my suitcase.

So I need something to use until the package I mailed comes.

It says 15.5 to 17 volts DC, 56 watts, and I have a whole bunch of
possible adaptors to use, but if I have to make one from a transformer
and diodes, how much ripple filtering would I likely have to do to
simulate the original power supply. None at all? So many microfarads
worth before and so many after the diodes?
Your basic regulated full wave bridge supply with a 470 uf cap across the
output will work just fine. Make sure it can deliver a steady 2 amps.

What is a "basic regulated" full wave bridge supply?
It's a basic regulated full wave bridge supply.
Repeating the words does little to clarify.
A "basic full wave bridge supply" is (to me) by definition UNREGULATED.

It is UNREGULATED when you drop the word REGULATED out of my description.
"It's a basic regulated full wave bridge supply"

Had I meant UNREGULATED my description would have been;
"It's a basic full wave bridge supply"

HTH
HAND

OK, listen up!
The op suggested using a transformer and some diodes and asked how much
capacitance to use on the output to properly power his laptop.
Your answer could be easily interpreted (by someone unskilled in the
art) to mean
that the suggested supply would work as long as it had 470uf and
delivered a steady 2 amps.
The fact that you stuck the word "regulated" into a discussion of
an unregulated transformer, diode, cap supply may make YOU feel better,
but it won't help the poor guy who thought he took your advice and blew
up his laptop.

YOU GAVE BAD, BAD, BAD ADVICE.

The possibility that YOU might have the experience, test equipment,
parts to make it work doesn't make it good advice for someone less
experienced/equipped in the context of THIER situation. Even if 100
of us could successfully implement it does not matter. The only
thing that matters is whether the OP could be successful.

Most of the questions asked here are from people who have not a clue
about what they're asking. That's why they're asking. It's clear
from the wording of the question. They want a simple solution to
a possibly complex and inadequately specified problem.
They have no way of sorting bad advice
from good advice. Stated another way, if they had the experience
to tell good advice from bad, they probably would not have had
to ask the question.

Most of the solutions presented to those questions are ill conceived
given the context of the question and the obvious lack of experience
expressed by the questioner.

The key to teaching is to put yourself in the shoes of the person
asking the question, understand what's being asked and deliver advice
in a context that can be understood, unambiguously and SAFELY executed by
the questioner with HIS level of experience and tools...not yours.

You also have to make some assumptions about what he didn't ask
and the ramifications of those missing pieces. Those unknowns
need to be addressed by further questions or a tutorial on other
factors and how they affect the answer.
Competency doesn't hurt.

Many of the newbie questions asked here would be properly answered by,
"given the level of experience suggested by the formation of your
question, the risk/reward ratio of this endeavor is unfavorable
....and here's why..."
Problem is the "here's why". To state that would require...there's
that word again...competency.

The handle fits, wear it proudly...