[sdiy] Variable power supply

[Richie Burnett]

That Tenma power supply is fine.  Agilent E3631A's are nice with multiple 
outputs.  Very clean linear regulation and digital readout, but as you said 
a bit heavy!  If you're picking one up second hand, the rotary encoders on a 
lot of Agilent gear of that era have a habit of going bad too.  We have 
loads of power supplies in our student labs where I'm currently working, so 
I tend to see what lasts and what dies quickly.  If you're kitting out a 
workshop and can justify the expenditure for your business, TTi's CPX400DP 
is a very nice power supply indeed.

About the only common power supply that I wouldn't recommend are these:

http://www.maplin.co.uk/p/100w-slim-bench-power-supply-n93cx
http://www.rapidonline.com/electrical-power/voltcraft-lsp-1205-single-output-100w-dc-power-supply-51-6777

We got a bunch of these a few years ago when they were on offer for £40 and 
they've all popped their mains fuses and died.  The same power supply is 
available from Maplin, Rapid, Farnell and many other suppliers badged under 
a different name.  They would be nice slim and light switching power 
supplies if they worked properly, but they seem to have something wrong with 
their control loop stability.  Just connecting and disconnecting a resistive 
load repeatedly resulted in random buzzing noises inside the one I tested, 
large random voltage overshoots at the output, and eventually a big bang, 
popped mains fuse and a piece of dead MOSFET rattling around inside the 
case.  My recommendation would be to avoid these, (but they might have fixed 
the design now, so YMMV!)

-Richie,


-----Original Message----- 
From: Tom Bugs
Sent: Saturday, March 05, 2016 1:42 PM
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Variable power supply

Last year I picked up this roughly £100-ish Tenma unit:
http://cpc.farnell.com/tenma/72-10500/power-supply-2ch-30v-3a-adjustable/dp/IN06824
It seems perfectly fine! (though if I were investing a bit more I'd sure
look for HP/Agilent/Thurlby etc)
I did look around quite a bit before plumping for this one.
Useful having the quickly & accurately adjustable voltage/power even if
you leave them set to one value 99% of the time.
Also very helpful having the current draw clearly displayed so you know
what the circuit is drawing.

On 05/03/2016 12:07, Phil Macphail wrote:
> Depending on your definition of inexpensive, I have picked-up several
> Agilent E3631A PSU¹s for around 200 Euro. They use the 34401A circuits for
> measurement, so the output voltage reading is pretty accurate and they are
> built to last. Postage costs can be significant though, as they are quite
> heavy,
>
>
> Phil
>
> On 05/03/16 03:57, "Synth-diy on behalf of Joel B"
> <synth-diy-bounces at dropmix.xs4all.nl on behalf of
> onephatcat at earthlink.net> wrote:
>
>> Hi,
>>
>> What would folks here recommend for a relatively inexpensive variable dc
>> power supply for the synth electronics experimenter?
>>
>> Joel
>>
>> Sent from my iPhone
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>> Synth-diy mailing list
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