[time-nuts] power supplies

[Tim Shoppa]

Jim, when it comes to "bench supplies" - knobs for voltage and meters -
most of the commonly available Chinese bench supplies in the under 3A-range
are linear with series regulator.

This unit (HY1803D) is typical and has a transformer (relay-selected
winding depending on the voltage setting) and a 2N3055 heat sink on the
back.
http://www.mastechpowersupplies.com/variable-regulated-power-supply-hy1803d.html

After you get to the 5A range they start becoming switchers. There are only
a couple of common designs with different trim and brand names on the front.

Of course old-school (50's-80's era) regulated HP bench supplies are
commonly available on the surplus market and they are built like tanks and
pretty much infinitely repairable as long as the meters haven't been
smashed in.

I would be reluctant to use a bench supply for long-term use because you
bump that knob and what was supposed to be 3.3V becomes 18V.

Few to no current production wall warts are linear. Power-conserving
regulations around the world now pretty much require wall warts to be
switchers. Linear (including regulated) wall warts are still available from
the surplus outlets but they are less common than before.

Few to no current production modular fixed-voltage supplies are linear.
With a handful of exceptions (I think a couple of the Lambda linear modules
are still available) they are almost all switchers.

Tim N3QE



On Fri, May 1, 2020 at 2:52 PM jimlux <jimlux at earthlink.net> wrote:

> What with telework, I'm doing more timenuts-ey stuff at home, and the
> power supply conundrum has come up.
>
> There's a plethora of interesting widgets scattered across my bench
> requiring variously, 5V, 8V, 12V, and 15V.
>
> I've got a box full of various fixed voltage supplies, mostly linear,
> picked up over the years.
> I suppose I can package a bunch of those up in a bigger box with banana
> jacks or binding posts.
>
>
> And then there's some things where you'd like current limiting and/or
> variable voltage.
>
> So I've started looking at inexpensive bench power supplies - there
> appear to be dozens, if not hundreds, of these available.  There must be
> dozens that are all very similar - They're switchers for the most part,
> displays, etc. for $50-100, from different vendors, all similar.
>
> Are they essentially commodity? Or are there particular brands that are
> good or bad?
>
> Are they all noisy?
>
> Weird UI problems (7 menu layers with a single knob)?
>
>
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