Hi Guys,
I'm trying to connect a 8 channel relais module (active low) to my arduino but i can't get it to work. I think i tried litterly everything but i want to check with you guys. Am i missing something, or is my (new) part just broken).
I dit:
Arduino Uno (powered via PC/USB)
8 chanel 5v relay board
External 5v power supply connected to JD-VCC and GND of the relay board
Arduino pin 1 t/m 8 connected to board IN 1 t/m 8
Arduino on a basic testcode:
pinmode(1, OUTPUT)
digitalwrite(1, LOW)
I cant get any of the relays to switch in any way. What am i missing???
With an external supply you need to remove the JD-Vcc jumper, and put the Arduino 5V onto Vcc, else there's no circuit for the led in the opto isolator.
edit: see circuit diagram here at yourduino.
You also shouldn't use pin 1 (or 0) for everyday IO.
thanks for your help
I removed the jumper. The VCC pin between the JD-VCC and GND is empty now.
i connected the VCC next to the IN pins to the 5v from arduino. Still no result
I also tried to connect the arduino 5v to the VCC between de JD-VCC and GND. Also no result.
Sounds right but let's see the whole Arduino code, and a drawing of your connections maybe?
Hi,
Have you got the gnd of the relay board connected to the gnd of the Arduino?
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom.. 
TomGeorge:
Hi,
Have you got the gnd of the relay board connected to the gnd of the Arduino?
Didn't seem like it, and with that board he shouldn't, since the Arduino only needs to give Vcc and a low data pin to activate the led in the opto. (Not sure of you were asking because you think he should or shouldn't have a common ground.)
Hi,
Just that when you look at the input pins as well as a Vcc there is a GND pin.
I agree that pull down active shouldn't need a gnd.
Tom...
Are you connected like this?
Graphic by @dlloyd.
BTW, don't use pin 1, it's the serial TX pin, and the relays are energized when the output pin is driven LOW.
Santepeter85:
... I'm trying to connect a 8 channel relais module (active low) to my arduino but i can't get it to work. I think i tried litterly everything but i want to check with you guys. Am i missing something, or is my (new) part just broken)...
The easiest way to test these boards is to not use any Arduino at all.
Get a 5v power supply, and first check that it is putting out 5 volts.
Then connect it properly to VCC and ground of the relay board, and (with the power jumper on) then take another (+) wire and try touching all the relay input pins one at a time. This should flip the relays on/off. If it doesn't, then something is wrong with the board.
Doug384:
The easiest way to test these boards is to not use any Arduino at all.
Get a 5v power supply, and first check that it is putting out 5 volts.
Then connect it properly to VCC and ground of the relay board, and (with the power jumper on) then take another (+) wire and try touching all the relay input pins one at a time. This should flip the relays on/off. If it doesn't, then something is wrong with the board.
Correction:"then take another" (-) not + "wire and try touching all the relay input pins one at a time." electricity only flows negative to positive. Not positive to positive.
