Connecting the relay

[moskovskiy82]

I have a project with 4 relays and several sensors. I was wondering how to connect all this.
As the picture below shows that connecting the relays to the same power supply as arduino is not working. Relay doesn't get disconnected or connected. Only the led lights up or dims a little bit. And feeding all of them through arduino is above its current limit on 5V pin...

[sundberg84]

Hi!

There are many threads about power and relays in the forum - I have had relays you need to connect ground through the arduino before it works. Try that (ie take your not workig schematics but move ground to arduino and see what happens).

[vil1driver]

This post is deleted!

[moskovskiy82]

@sundberg84

Nope. Connected GND to arduino leaveing external VCC. Same result

[sundberg84]

@moskovskiy82 Ok, next i would try to change power supply and se what happens.

[moskovskiy82]

Done. Took another powersupply )which can only go 4,5 or 6V but at true 2Amps output. Same thing.

[moskovskiy82]

The problem as i can see it doesn't go to off properly. Going to on state is fine.

[rvendrame]

@moskovskiy82

The 5V and VIN pins are not the same thing, per original arduino nano schematics.

Usually the relay "click" generates some noise on the power lines, which may disturb ( = freeze, hang) arduino and/or nRF radio.

Maybe once you connect it through the 5V, the regulator is reducing that noise? You might try to add capacitors between relay's VIN and GND, 47uF could be a starting point.

[moskovskiy82]

@rvendrame

Well yes. I understand that Vin passes everything through the voltage regulator. This is why i am surprised that the relay works while being fed throught the 5V pin of the arduino and doesn't work when connected directly to a 5V supply.

[moskovskiy82]

@rvendrame

Thank you!!!! The scheme solved it all!
Connecting 5V t6 Vin resulted on voltage drop. So the D1-D13 pins produced less than 5V which was not enough for the in pin

[rvendrame]

@moskovskiy82 , it makes sense. Glad you ruled it out!