Can't turn on 12v relay with output pins

Using Arduino General Electronics
21

Where ?

22

Just way too much current drawn seems to be the challenge,

23

20211130_141644
20211130_1416441920×2560 372 KB

I have gotten it to work before with 15 pins driving relays on the board, not sure why ot suddenly won't cooperate.

24

But why is it not too much current for the 5 and 3.3v pins?

25
  • Try the test in post #18.
26

Because the current from those pins come from the power supply. The 3.3V regulated output is able to supply 150 mA max (limit of the 3.3V regulator) and the 5v pin way more than this depends on how you are powering the board but multiple hundreds of mA (up to 800 if my memory serves me well)

Contrast that with digital pins which can provide only a peak current of 40mA and should be kept at 20mA to play safe

27

Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, component names and pin labels.

We need to see a proper diagram as you have your circuit connected, reverse engineering can help find any errors.

Thanks.. Tom... :smiley: :+1: :coffee: :australia:

28

20221207_104907
20221207_1049071920×2560 133 KB

Here it is drawn out, power supply is 12v.

29

if you look at this very similar board with only 2 relays they do state in the description

Hinweis:
Dieses Relais wird durch DC 12 V ausgelöst, kann nicht mit dem Arduino-Signal bei 5 V auslösen.

30

One last time.

Try the test in post #18.

31

According to the Amazon link, This is the schematic of this board

image
image1454×1500 119 KB

So if you want to drive with 5v Vcc probably needs to be 5V and JD-Vcc will be 12V.

But for that you need this P9 connector, I don’t see it in the picture

32

The schematic they offer does not appear to match the PCB layout.

:thinking:

image
image1666×804 90.7 KB

33

Not a big surprise :wink:

34

Hi, @cjacobs61
Please run this simple code and observe the relay and the LED on the relay PCB.
Open the IDE monitor and set the baud speed to 115200.

The onboard LED on the MEGA should also flash ON for HIGH output and OFF for LOW output.

byte relayOutputPin = 10;
byte onboardLED = 13;

void setup()
{
  Serial.begin(115200);
  Serial.println("==== Relay Test Code===");
  pinMode(relayOutputPin, OUTPUT);
  pinMode(onboardLED,OUTPUT);
}

void loop()
{
  digitalWrite(relayOutputPin, HIGH);
  digitalWrite(onboardLED, HIGH);
  Serial.println(" Output pin == HIGH");
  delay(1000);
  digitalWrite(relayOutputPin, LOW);
  digitalWrite(onboardLED, LOW);
  Serial.println(" Output pin == LOW");
  delay(1000);
}

Tom.. :smiley: :+1: :coffee: :australia:

35

Just a Note.
The onboard LED Pin13 on the Nano will switch on when the Pin13 is Low , the Led is connected to the Positive supply so it will not follow the same ON/OFF pattern of what is measured on Pin13.

Not sure about the Mega on board LED but might be the same.

36

Hi,

All my Nanos have LED cathode to gnd, and flash ON when D13 HIGH, Mega is the same.
Arduino_Nano-Rev3.2-SCH.pdf (80.5 KB)

Tom.. :smiley: :+1: :coffee: :australia:

37

Interesting.
I did a long while back put a LED on pin 13 and the LEDS(with Blink) did not Blink together.
I will for sure do the test again.
Apology in advance for my mistake.

38

same here, also for UNO

39

That code fixed it! I'm not sure what the difference is between how I was setting the pins to high vs this code, though.

40

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