[time-nuts] Low noise power supplies?

Max Robinson max at maxsmusicplace.com
Fri Feb 1 14:39:14 EST 2013

Well, I stand corrected.  Weren't the TM 500 instruments marketed as low 


Max.  K 4 O DS.

Email: max at maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site 
Music site: http://www.maxsmusicplace.com

To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe at yahoogroups.com

To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe at yahoogroups.com

To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe at yahoogroups.com

----- Original Message ----- 
From: "David" <davidwhess at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, January 31, 2013 11:10 PM
Subject: Re: [time-nuts] Low noise power supplies?

>I have seen it used in a couple of Tektronix TM500 instruments but the
> purpose may have been to generate a lower voltage power supply rail
> instead of noise reduction.  Tektronix often added LC sections on
> their switching power supply outputs and distributed smaller LC
> sections to prevent coupling between different circuits.
> On Thu, 31 Jan 2013 22:12:42 -0600, "Max Robinson"
> <max at maxsmusicplace.com> wrote:
>>You haven't seen it used because it doesn't work very well.  It appeared 
>>a few pieces of Heathkit equipment but I don't think HP or Tek used it at
>>all.  Any AC component of base to collector voltage has a small but 
>>effect on Vbe which transfers voltage in the reverse direction from
>>collector to emitter even though the base is held at AC ground.  A three
>>terminal regulator does a better job of suppressing ripple from a power
>>Regulators use a zener diode as the reference and there are circuits in
>>which a zener is used as a noise source.  What does that tell you?  The
>>quietest power supply is an analog regulator followed by one or more RC
>>filter sections.  The inductor in an LC filter is likely to pick up more 
>>and noise than it filters out.  My presumption is that a low noise power
>>supply is likely to be providing a small amount of power to the load and
>>load regulation is probably not a problem.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

More information about the time-nuts mailing list