Listmates,
After seeing many posts along the way for people wanting/needing RF quiet wall
wart supplies, here is something that might help. Follow this link:
http://www.mpja.com/05-07-13.asp?r=166888&s=2
This little gem is an unregulated 15V, 1 amp wall supply. How do I know it's a
linear? It has all of the right info: 1) Switchers are inherently regulated.
2) The rated voltage input is given as 100 to 120 VAC, 50/60 Hz. No options.
3) Weight - it weighs over 1 pound. I have a switcher with equivalent output
and it weighs just over 3 ounces!
The listed output is probably at full load of 1 amp. At lesser loads, the
output voltage likely swings as high as 20 volts, maybe even a tad more. This
"wart" is almost certainly nothing more than a transformer, diode, and
capacitor (and maybe a high value bleeder resistor). And one can be yours for
a whopping $1.99.
Given that linear supplies are getting a bit rare these days, this unit could
provide the foundation for any supply you might need for 5, 6, 8, or 12 VDC
using the LM78-series of regulator ICs. They are easy to use and also low
cost. You could build up a small perf board with the regulator on it to
provide regulated DC power for projects or gadgets that are driving you nuts
with the RFI from their el cheapo switchers. Folks, it is not going to get
much cheaper or easier than this. There are a few on-line sources that do
supply fully regulated linear supplies (JAMECO Electronics being one of them),
and if you need more than 1 amp, you'll need to get one of those. But if your
project or gadget draws less than 1 amp and needs one of the listed voltages,
grab one of these, the required regulator chip, and a few other parts. Who
knows - you might even enjoy the home brew experience of fixing a nasty problem
yourself. Have fun.
Note: I have not included a 15V listing because linear voltage regulators (like
the LM78-series) need "headroom" in order to operate correctly. While there is
such a thing as an LM7815, you need to make certain that you have at least 18
VDC available at the input pin of the chip so that it can source properly
regulated 15 VDC to the load.
I have no connection whatsoever with either Marlin P Jones & Associates or
JAMECO Electronics. I am just a happy customer of both firms.
73, Dale
WA9ENA
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