[time-nuts] Thunderbolt Supply

[shalimr9 at gmail.com]

My original (red box) T-bolt runs off a 28VDC supply. For that, it has a built-in DC/DC converter. The specs are the same as they are for the more common (and more recent) version.

You do not need rocket science to make a switcher quiet enough for most purposes, just care and good engineering.

When circuits are extremely sensitive to supply noise (I mean by that way out of the ordinary sensitivity), the problem may be with the circuit design rather than with the supply.

Didier KO4BB

Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: Magnus Danielson <magnus at rubidium.dyndns.org>
Sender: time-nuts-bounces at febo.com
Date: Tue, 15 Feb 2011 10:47:31 
To: <time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Thunderbolt Supply

On 02/15/2011 04:18 AM, Charles P. Steinmetz wrote:
> Bob wrote:
>
>> If all you are doing is running a Thunderbolt, you don't need a supply
>> that's more quiet than most batteries.
>
> Most batteries are *very* quiet -- it takes heroic measures to get *any*
> actively regulated supply into that ballpark. Indeed, one might be
> tempted to run a Tbolt off of three batteries, each one charged by a
> low-noise, high-impedance current source that puts out about .05 CV more
> than the Tbolt draws. One could even turn the charging off for short
> periods of "minimal noise" operation, if the batteries were suitably
> sized. However, in either case I would be concerned that the drift of
> one or more of the battery voltages (poor absolute regulation) might
> introduce another source of XO drift -- but I have not tried it.

This has gone overboard. The T-bolt generates digital noise all by 
itself. It's the OCXO which would benefit most from a clean supply and 
isolation from the rest of the T-bolt except that temp-sensor.

Providing ultra-clean supplies to the digital logic would be overkill, 
as it would mess it up itself anyway.

Cheers,
Magnus

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