[sdiy] 4069 vco gives v+ noise?

[Michael Buchstaller]

>The 50 Hz (it looks like you are in Europe) and comments about
>additional load makes one suspicious of the power supply. 

Assuming he is using a full-wave (bridge) rectifier, the PSU noise
from insufficient headroom of the regulator would be 100 Hz.
But yes, my first bet is a transformer in the PSU with a voltage rating
too low, so it sags under the load of additional modules.

>The supply
>I am using is a cheesey home built wallwart transformer, half wave
>rectifiers with 78xx and 79xx regulators.

Yes, half wave rectification would show 50 Hz hum.

Maybe one of the other modules is connected to the outside world and
allows hum to come in the system ?


-Michael Buchstaller