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I have bought this Grove relay: Grove - Relais | Kiwi Electronics. I use it to drive a low-power water pump with a 9v battery. So the pump circuit is isolated from the Arduino circuit. When the Arduino sends 'high' to the relay, this relay begins to stutter. Contract-release at high frequency. This only happens if the pump is attached. I have bought multiple relays and they all behave in the same way. When I use a non-grove relay, such as Twee-kanaals 5V relais module | Kiwi Electronics I do not have this issue. I made a small film of both relays: https://photos.app.goo.gl/szHHE5EGqjHzJy3f7 (shared google photo's album). Why does this happen? What can I do to correct this issue with the Grove-relais? I want to use these Grove-relays because they need to be used by students that are used to work with Grove components. Please help!

The code:

void setup() {
  Serial.begin(9600);
  pinMode(7, OUTPUT);
  Serial.println("start");
  delay(1000);
}

void loop() {
  digitalWrite(7, HIGH);
  delay(2000);
  digitalWrite(7, LOW);
  delay(3000);
}

This is the schema: enter image description here

Juraj
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mvermand
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  • Please try the grove relay again with the exact same connections and code as the other relay. If it then still happens, then the relay board is probably broken – chrisl Feb 22 '24 at 13:59
  • I use the exact same code and arduino setup. I tested it with multiple different Grove relays. They all have the same issue. – mvermand Feb 22 '24 at 14:40
  • could be bad code – jsotola Feb 22 '24 at 14:51
  • The circuit works properly when I switch to the non-grove relay. And it's just setting a digital output port high. Can't be much bad about that, i think. :-( – mvermand Feb 22 '24 at 14:59
  • maybe the arduino is resetting – jsotola Feb 22 '24 at 15:17
  • Have you tried triggering the relay by directly attaching the relays input pin with ground and 5V? You need to narrow down the source of the problem. Currently we don't have much to work with. Please also include your code in the question, so that we can check that too. – chrisl Feb 22 '24 at 19:50
  • yes indeed, it is resetting, but I do not understand why. It only happens when I put the load on the high-power side of the relay. Without the pump attached, the relay just functions fine. I tested two relays, both show the same behaviour. So adding a load on the high-power side affects the low-power side?! That should be completely isolated, right? – mvermand Feb 23 '24 at 07:50

1 Answers1

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The Grove relay in your photo (the black one) clearly says DC3V: you are presumably energising the coil, as well as controlling it, with DC5V.

Perhaps you should try their 5V version:

enter image description here

user95861
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    The datasheets says the 3.3v version can be operated both at 3.3v and at 5v. It has a 5-3.3v shifter a board: https://wiki.seeedstudio.com/Grove-Relay/ – mvermand Feb 23 '24 at 07:54