[time-nuts] Switching regulator replacement for 7805

Chris Albertson albertson.chris at gmail.com
Sun Dec 4 14:45:02 EST 2016

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 at febo.com> wrote:

> I found a cute little switching regulator that's a drop-in replacement for
> an LM7805: http://www.ebay.com/itm/261243604047
> I got a couple to play with, mainly to see how bad the noise would be.
> Here are spectrum analyzer and PN shots comparing a cheap surplus OCXO when
> driven by a regular 7805 and by the switching replacement.
> The switching frequency is supposed to be 2 MHz but you can see that it's
> more like 2.4 MHz.  Whether this performance is sufficient for any
> application is up to you.  It sure runs a lot cooler than a 7805, though!
> John
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Chris Albertson
Redondo Beach, California

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