[time-nuts] Low noise voltage regulators

Arnold Tibus Arnold.Tibus at gmx.de
Wed Feb 24 22:59:23 UTC 2010


Hi,

NS gives some informations about improvements in their AN-173.pdf
http://www.national.com/ds.cgi/LM/LM117.pdf
Audio freaks are discussing it in
http://www.diyaudio.com/forums/solid-state/28978-improving-lm3x7-regulator-circuit.html
Is that what you are looking for?

73
Arnold


On Thu, 25 Feb 2010 11:22:02 +1300, Bruce Griffiths wrote:

>You can improve the performance of the LM723 if one substitutes an LM329 
>for the internal reference biased from the regulator output.
>The trick is to use the internal reference for startup and decouple it 
>with a diode or similar once the LM329 achieves its nominal output.

>Currently, there appear to be 2 variants of the LM723 one (made by 
>National) that uses a noisy bandgap reference and another variant that 
>actually uses a quieter zener reference.

>Bruce

>Brooke Clarke wrote:
>> Hi neville:
>>
>> My old Gibbs rack mount 5 MHz standard used the LM723 linear 
>> regulator.  I believe it's one of the lowest noise regulators you can 
>> use.
>> http://www.national.com/mpf/LM/LM723.html#Overview
>>
>> Have Fun,
>>
>> Brooke Clarke
>> http://www.PRC68.com
>>
>>
>> Neville Michie wrote:
>>> Hi,
>>> I remember a reference, probably by Bruce, that LEDS provide a low 
>>> noise voltage reference.
>>> I am proposing to build a voltage regulator for a thermally 
>>> controlled LPRO rubidium oscillator,
>>> with the voltage regulator being mounted on the 0.5 inch thick 
>>> aluminium heat sink plate.
>>> The LEDS would also be mounted on the plate, which has controlled 
>>> temperature.
>>> The LPRO has internal voltage regulation, and by running it at ~40C 
>>> and 18Volts, the thermal
>>> flux within the unit is minimised as is the power demand.
>>> What I want to know is if a LM317 running on a stack of LEDs driven 
>>> by the LM317 output
>>> would provide a low noise power source? What would be better?
>>>
>>> cheers, Neville Michie
>>>







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