2x Arduino: One as a power supply, One actioning 4 relays

Other Hardware General Electronics
41

If you only have 4 realys to drive on the Adruino, don't use the 2803.
jumper JD-Vcc to VCC, Arduino +5 to relay VCC, arduino GND to relay GND, Arduino o/p pin to IN1 and IN2.

42

LarryD:
If you only have 4 realys to drive on the Adruino, don't use the 2803.

In this stage a have only 4 relays. The finished project will have at least 10 relays...

LarryD:
jumper JD-Vcc to VCC, Arduino +5 to relay VCC, arduino GND to relay GND, Arduino o/p pin to IN1 and IN2.

That's how i used it so far...
But when i turn them on, i don't have 5V on Ardiono +5V pin anymore...
That's why i want to supply power for them from an external power supply (EPS).
So it will go something like this: connect the relay's VCC to the EPS +5V, the relay's GND to the EPS GND, and the INT1 and INT2 to the Arduino digital pins...

43

Connect the 2803 o/p to IN1 or IN2 then External +5V (not the Arduino +5) to Relay VCC/JD-VCC.
In this case a HIGH on the o/p of the Adruino will close the contacts.

Of course Arduino GND to relay GND to external supply GND.

With 10 relays use the 2803.

44

LarryD:
Connect the 2803 o/p to IN1 or IN2 then External +5V (not the Arduino +5) to Relay VCC/JD-VCC.
In this case a HIGH on the o/p of the Adruino will close the contacts.
Of course Arduino GND to relay GND to external supply GND.
With 10 relays use the 2803.

After i saw your message, this is what i understand (keep in mind that i'm from Europe :smiley: ):

  • Connect 2803 o/p to IN1
  • Connect EPS +5V to Relay VCC
  • Connect ALL the GND line together
    -> And what about the Arduino pin? Where to put that?

See the schematic:

ULN_R-1.jpg
ULN_R-1.jpg3051×1194 396 KB

45

Arduino O/P Pin 31 to 2803 pin 1
2803 pin 18 to relay IN1 or IN2

Relay JD-VCC to relay VCC to EPS +5V to 2803 pin 10.
Relay GND to Arduino GND to 2803 pin 9.

46

Note: in your last schematic you should have 2803 pin 9 to GND

47

LarryD:
Note: in your last schematic you should have 2803 pin 9 to GND

Yes, sure. I was hurrying...

Ok. So, like in the attachment right?
I did this same thing in the first schematic. But i didn't know if it will work. :smiley:
I'll give it a try when the 2803s arrive... :smiley:

ULN2803 Relay Module_bb.jpg
ULN2803 Relay Module_bb.jpg3051×1191 386 KB

48

Good for you, you have got it!

49

LarryD:
Good for you, you have got it!

Thanks!

I hope that the admin won't close this post, or ban my user because i'm responding so many times and the post is getting longer and longer... :smiley:
I hope i won't bother again until the parts arrive and my project is almost finished.
Thanks again for all the help! You are doing a really great job with this forum!
I'm goin to sleep. :smiley: It's almost 5 in the morning. :slight_smile: