[time-nuts] Switching regulator replacement for 7805
jimlux at earthlink.net
Sun Dec 4 14:32:29 EST 2016
On 12/4/16 10:50 AM, John Ackermann N8UR 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!
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.
As I recall, they're in that 2 MHz-ish frequency as well.
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