I have 16 channel relay shield and cant turn on all relays.
Then I connet arduino tu PC all relays works fine (all at once) but then I disconect arduino from PC and power on 12V power supply all relays start blinking, looks like they dont have enoth power. If I use only 5 at once everything is ok.
I dont connect 12V to relay shield:
can this be the reason?
all 16 relays are connected to 220V