[sdiy] LED current source needed for 'digital' outputs?

[Neil Johnson]

Mattias Rickardsson wrote:
> With this constant-current approach you can also avoid varying
> currents, which are possible causes of disturbances in nearby
> circuits. On the other hand it might get impossible to avoid varying
> voltages, which can disturb nearby circuits in another fashion. :-)

Voltage fluctuations you can localise.  Current fluctuations affect
the entire length of the power rails back to the PSU, although
hopefully only as far back as the next bypass capacitor!

Neil
--
http://www.njohnson.co.uk