[time-nuts] Low noise power supplies?

[Bob Camp]

Hi

To answer the original question - Power Design makes some pretty quiet bench
supplies. If you are doing low noise testing, batteries often will let you
get rid of one more ground loop. Even well built power supplies are not as
well line isolated as a battery.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Charles P. Steinmetz
Sent: Thursday, January 31, 2013 5:33 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low noise power supplies?

Lester wrote:

>For a regulated power supply, make one using a 723. The 723 has
>far lower noise out than the monolithic regulators.

If you are willing to design your own regulator using a 723, you may 
as well use a few more parts to get a much better result.  Neither 
the internal reference nor the internal error amp in a 723 is 
anywhere near state of the art today with respect to noise, tempco, 
or speed.  Using readily available buried zener references and 
low-noise, high-speed op amps (or even a few discrete transistors), 
you can do several orders of magnitude better than a 723 in all 
respects.  The web is overflowing with designs (though not all of the 
circuits you find perform as advertised, so evaluate them with a 
critical eye and use your own sound judgment).

But wasn't the original question what is available off-the-shelf?

Best regards,

Charles




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