Advanced Member level 4
We have signals from microcontroller outputs, when do we need to use relays as intermediate devices apply for these signal to control external devices ?
And could you help me with these questions: when PIC is normal operation, has supply, what is the state of output pins if we not affect on them(e.g send a "1" or "0" signal to that output) ?
uhm ... across which device :|connect a diode or RC snubber across it so avoid damage....
:?: so I don't need NOT gate (means output signal be "1" for control external device ?)Make it simple. A darlington setup is likely not necessary. Try a single NPN in a configuration like this
Let me check again, thank youOther thing in your schematic: C1 is a little small. Have you calculate it?
Your input ripple to the 7805 is very high now. If you make the capacitor bigger your circuit will be more stable.
If your circuit draws 100mA the capacitor should be about 100 µF to get a ripple of ~1.5V.
For a bridge rectifier:
(Uripple = ~1.5*(Io/C) (Io in mA, C in µF)