[time-nuts] Wenzel, Inc article on low-noise oscillators
bruce.griffiths at xtra.co.nz
Wed Jan 23 19:45:25 EST 2008
John Ackermann N8UR wrote:
> By the way --
> Despite the discussion in the article about the voltage regulator, TVB
> and I have discovered that the Wenzel ULN oscillators are very sensitive
> to external factors like power supply noise. When I was testing with an
> aged bench supply that apparently had some dried up electrolytics, the
> close in noise was degraded by as much as 20 dB from the spec. With a
> really good power supply, spec was met easily.
A low noise regulator doesn't necessarily have high line rejection.
This is particularly true for some discrete implementations.
For example "super regulators" using an AD825 error amplifier without a
Implementations using discrete transistor error amplifiers may have even
lower line rejection.
Wenzel's active noise cleanup circuits arent particularly effective at
low frequencies unless you cascade several and increase the loop gain by
adding another transistor.
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