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?
I have a 40 year-old EICO kit scope that I've never fully understood how to use -- I bought it used and assembled -- but this might be the push I need to finally learn how to use it for something more than the most basic use. I also have loads of diodes and an assortment of capacitors of all sizes, plus I can buy more if I need to. But since this is only for a few weeks, until the box comes in the mail, and I'm not going to be going anywhere with it, I don't want to go to more trouble than necessary.
Thanks.
If you are inclined to email me for some reason, remove NOPSAM :-)
What is a "basic regulated" full wave bridge supply? The terms "regulated" and transformer/diode/cap seem to be incompatible. If I understand what you wrote, it's a very risky recommendation for someone skilled in the art. But someone skilled in the art would not have asked the question.
If you don't have a REGULATED power supply within the allowable range, give it up. If the original posting is an accurate description of the thought process, the OP should do his laptop a favor and wait for the mail.
Won't work for you, because you're at home and your supply is in the mail, but...on the road, when I've lost or forgotten various common supplies, I've done this: go to the desk clerk and ask to look at supplies left behind by former guests.
If your laptop, or cell phone is a common brand/model, there's at least a chance they'll have the exact one. If you have a problem with appropriating someone else's property, just leave it in the room when you check out (for the next guy).
Repeating the words does little to clarify. A "basic full wave bridge supply" is (to me) by definition UNREGULATED. If it's regulated, the fullness and waveness and bridgeness is irrelevant to the load. Or the pile of smoking plastic that once was the laptop in question.
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.
Be worth getting a learner book on electronics since things like values needed for smoothing a given power will be explained. And the fact that the DC voltage produced from an AC one depends on the type of rectification too. So if we look at the basics, 56 watts @ 17 volts is 3.3 amps. Full wave rectification gives approx 1.4 x the AC supply To smooth 4 amps needs 10,000 µF.
So a 12 volt 4 amp transformer, 4 amp bridge rectifier, and 10,000 µF should give you 16.9 volts adequately smoothed.
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*Black holes are where God divided by zero *
Dave Plowman dave@davenoise.co.uk London SW
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