[time-nuts] homebrew 13 dBm distribution amplifier based on NIST design 5 to 100 MHz

[Bruce Griffiths]

Poul-Henning Kamp wrote:
> In message <qlcld41iisd7o6jq43o4tpbi3bgievgr6h at 4ax.com>, Gerhard Hoffmann write
> s:
>
>   
>> The question is more if the 100r * 100u do anything to de-noise
>> the LED voltage. Close to the carrier probably not. The problem is
>> that you nowhere get exact numbers to base a decision on.
>>     
>
> Be aware that LED's work both ways: current->light and light->current.
>
> Their noise spectrum is influenced by the ambient light, in particular
> flourecent lights, other discharge types, and, ironically, modulated
> LED lamps.
>
>   
Poul

In practice this isnt usually a significant problem with a forward 
biased LED as the photocurrents are relatively small compared to the LED 
bias current.
One can always use a light shield or coat the LED in opaque epoxy.

Bruce