For those of you that run outdoor lights in your buildings using the bulbs from the “malibu” lights, you may be shocked with the price of the power supplies. Around here, simple 75w power supplies are about $50.
This page describes how to build a power supply from an old computer PS. You can build a 300+ watt supply for next to nothing.
http://web2.murraystate.edu/andy.batts/ps/powersupply.htm
-=Bob
Bob,
Your link is not showing. Yes, those power supplies are really up there in price.
Crikey, the link worked this morning!
Here’s another one:
http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
Howdy!
As they point out in the article, these things are SWITCHING supplies, and require some sort of load to be connected at all times. A personal computer, even when it isn’t doing anything significant, presents a considerable current drain just to keep the microprocessor running… thus the need for a “power waster” resistor. Without it, a lot of switching mode supplies won’t even start.
In this respect, switching mode supplies are useful for the same reason Diesels are used in over the road trucks (and locomotives); they work best when they’re producing a constant amount of power without significant load variations on a continuous basis.
Also, for a given power capability, a switching supply weighs a whole LOT less than a comparable analog power supply.
There are drawbacks tho…
The biggest one I run into every day is that switching supplies seem to fail a whole lot more frequently than analogs in continuous, 24/7 service. When that happens, SOP at work is to not even TRY to repair the supply; it gets pulled out and replaced as a module.
I’ve tried to repair switching supplies… it’s frustrating to the point that it’ll drive ya nuts! As a result, repairing switchers is way too expensive because it’s way too labor intensive.
IMHO… the “disposable power supply” concept is basically wasteful, and environmentally it’s a disaster.
On the other hand… since switchers are becoming more and more popular, an AWFUL lot of components for building your own analog supplies can be had for a song if you know where to look for them. we’re talking REAL bargains for very dependable home built power supplies.
As an example…
At a ham radio picnic, I picked up a power transformer that’ll probably wind up in a supply for my trains.
It has two primaries, 110 VAC each, which allows you to make the resulting power supply run on 110 VAC or 220 VAC at your option.
It has two secondaries, 16 VAC each at better than 20 amps!!!
Th manufacturer (General Electric) rates is at .750 KVA, or 750 watts into a resistive load!
This thing weighs in at about 15 - 20 pounds, and it cost me a whole two dollars!!!
Wandering the same Swapper’s Row would have also yielded up the rest of a hefty supply… high current bridge rectifiers for a couple of bucks… big, computer grade filter capacitors for next to nothing… industrial junk containing elaborate, high current pass transistor voltage regulators, almost for the asking.
We live in a society that has embraced Planned Obsolescence with a vengence; the amount of WASTE is unbelievable.
I’m glad to see somebody dealing with a second life for PC power supplies… but I consider them expendable (like the original designers and manufacturers did), and more troule than they’re worth. There are better ways to go out there, and IMHO that means analog.
Sometimes, older technology is the best.
Mr. T.
I posted the other question in this part of the forums because this write up is a little unclear to me. I’ve never had a computer apart and wouldn’t have a clue what part is the power supply. Is this capable of being put in a new cabinet or are you using the old computer cabinet? I guess it is best to answer this in my other question, if it is relative. Thank you for the consideration.
Computer power supplies are typically in their own metal box, as the illustrations in the link above show. You might be able to get some older ones free from a computer shop that works on computers. Often upgrading a computer requires a higher capacity power supply.
You could definitely put it in another cabinet if you wanted.
Regards, Greg
Greg Elmassian said:
Computer power supplies are typically in their own metal box, as the illustrations in the link above show. You might be able to get some older ones free from a computer shop that works on computers. Often upgrading a computer requires a higher capacity power supply.You could definitely put it in another cabinet if you wanted.
Regards, Greg
The good thing in the US is if you put it in the wrong position, it just does not work.
Now 220v applied in the 110v position, that’s nasty.
For a while Hewlett Packard set the power switch to the right voltage for the destination country, until someone took a US unit to the UK… boom!
From then on, they put the switch in 220 and put a note to check the voltage if it did not run right.
That of course, predated the auto-sensing ones, this was about 1978. (I worked there when the testing guys made a boom)
Regards, Greg
Seems to me most computer supplies deliver lots of current on the 5v, but only an amp or 2 on the 12v line.
Hmm. All-Electronics doesn’t seem to have interesting power supplies on special.
Greg Elmassian said:
The good thing in the US is if you put it in the wrong position, it just does not work.Now 220v applied in the 110v position, that’s nasty.
For a while Hewlett Packard set the power switch to the right voltage for the destination country, until someone took a US unit to the UK… boom!
From then on, they put the switch in 220 and put a note to check the voltage if it did not run right.
That of course, predated the auto-sensing ones, this was about 1978. (I worked there when the testing guys made a boom)
Regards, Greg
It didn’t happen again - we Araldited 'em. Notes assume the mongrels can read.