Thanks for this. I've seen something similar from Murata :

http://uk.farnell.com/murata-power-solutions/oki-78sr-5-1-5-w36-c/converter-dc-dc-1-o-p-7-5w-1-5a/dp/2102101

Since they're a mainstream supplier of inductors they may have managed
better performance - it would be interesting to compare.

On Sun, Dec 4, 2016 at 6:50 PM, John Ackermann N8UR jra@febo.com wrote:

On Sun, 4 Dec 2016 13:50:21 -0500
John Ackermann N8UR jra@febo.com wrote:

Cool! Thanks a lot! I wondered quite some time how much worse these
things would be. Did you also do some EMI measurements?
For what is worth, the spectrum below 1MHz looks pretty decent,
especially considering how badly done the layout on those boards
are. They must have completely ignored the layout guidelines in
the datasheet.. :-/

If you have the time and leasure, it would be nice if you could
compare them to the OKI-78SR series from Murata. I would suspect
they perform quite a bit better on noise and EMI...beside being
cheaper and easier to source :-)

		Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

On 12/4/16 10:50 AM, John Ackermann N8UR wrote:

I've used a bunch of the Cui 7800 replacement switchers - they're
typically in a 4 (or 9) surface mount DIP that's kind of tall for the 1
Amp version, and a sort of fat 3 pin through hole for the 0.5 amp
version.  I used the 1A parts because they have a "shutdown" pin and you
can adjust the voltage.

http://www.cui.com/product/power/dc-dc-converters/non-isolated/0.5-a-output-current/p7805-s-series

As I recall, they're in that 2 MHz-ish frequency as well.

Thanks for that pointer!  When I searched Digikey, I wasn't able to find
anything that was in the 3-lead TO-220 case.  I will definitely check
out the Murata units, as I suspect they perform better than this one.

John

On 12/04/2016 02:01 PM, Adrian Godwin wrote:

In message 5844656D.5010404@febo.com, John Ackermann N8UR writes:

Traco has had the TSN and TSR series for some years now, and they
perform nicely in all applications where I have plugged them in.

Havn't tried an OCXO though.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

And Digikey does stock the Murata part, for about $4.30.  Why I couldn't
find it when searching their site for switching regulators, I don't know.

John

On 12/04/2016 02:39 PM, John Ackermann N8UR wrote:

Surprisingly good as a drop-in replacement.

Question:  Suppose you are doing a new design and had space on the PCB for
one more small passive part.  I wonder how the performance of the switcher
with an LC filter compares with the 7805.    Yes, I think this is fair.  It
is a trade off, It costs me one more inductor but I gain hugely reduced
power consumption and heat.

Or stated another way:  You have shown the noise difference for drop in to
existing circuit.  What about two roughly equivalent new design circuits?
How much to we pay in dollars and complexity to get equivalent noise?

Thanks a lot for this work.  Headed over to eBay right now....

(My application uses LiPo battery and needs to have stable voltage as the
battery drains but my current solution is noisyand those 78xx chips waste
far to much power. )

On Sun, Dec 4, 2016 at 10:50 AM, John Ackermann N8UR jra@febo.com wrote:

--

Chris Albertson
Redondo Beach, California

On 12/4/16 11:39 AM, John Ackermann N8UR wrote:

The Cui parts are also available in a TO-220 pinout

Mouser has them  V7805-1000 for example, in a variety of configurations
and ratings, but a bit more expensive.. $5-10

Maybe you need to search for DC/DC converter or something?

I found them a few years ago because I was looking for surface mount
power converters

Seems there's tons of them from a variety of mfrs, judging from the
Mouser search engine

On 12/4/16 11:45 AM, Chris Albertson wrote:

What we just did was use a discrete Linear Tech DC/DC, with carefully
chosen output voltage, followed by a LDO with very, very good PSRR at
high frequencies.

You could probably do the same with the modular parts- saves you
designing the DC/DC - the Cui parts (and I'm sure the others) can adjust
the output voltage with a single resistor and they have very wide input
voltage range, although I don't know if they can do buck/boost, or just
buck.

For our application we had an existing DC/DC design, so in theory, we
saved time by reusing it - whether or not that's really true, I'm not
sure, different voltages, different load currents, etc.  It might have
been easier/cheaper/faster to use a modular DC/DC - assuming it doesn't
have some sort of latchup or other single event effects.