Hi Per,

maybe I understand you not right, have you real problems with noise or was it only an assumption ?


I think, a micro with internal code and data memory generate very less noise, especially, if you drive it over relays.

Some suggestions:
Use a 78L05 direct on the micro to generate its VCC.

Use luxurious the 100nF pills around it.

Furthermore all used IO-lines can be decoupled e.g. with 100 Ohms resistors in series direct on the micro. Then drive the relays with MOSFETs e.g. BS250 (low active).


Peter