[time-nuts] Switching regulator replacement for 7805

[John Ackermann N8UR]

That's a very good point... the design I'm testing the regulator in has 
a fair bit of C filtering, but no series L.

On 12/04/2016 02:45 PM, Chris Albertson 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 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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>
>
>