arduino power 8 relays

hello, can an arduino power 8 relays without a power supply? i connected the GPIO from arduino straight to the relay board, but connected the VCC and GND of relay board to a 9V power supply of 1A. however it does not seem to woek, it will only work if i connect it to the Arduino's VCC and GND. However, i am contemplating whether arduino is sufficient to power the relay without ant external power supply. i dont want to burn the arduino. has anyone have similar experience? if so, how did you solve it? thanks!


Sounds like you do have 2 power supplies., so make sure both grounds are connected together.

Ooh ok, so ground to arduino , relay and power supply? And vcc to power supply ?

It is ok to have the vcc, positive voltage separate, but keep the grounds connected.

Alright!! Thanks for the advice, will do that when I get back =) why though may I ask?

i connected the GPIO from arduino straight to the relay board

Show us a LINK to this please.

Hi, I don't have a link, it's just my set up..I just wire the digital output of Arduino to the relays input .

Then this might help you:

hi,i connected the GND from the power supply to the arduino and relay board and connected the VCC directly from power supply to VCC. the relay board lights appear very dimly and a high buzzing sound is heard. it is not like this when i connect the relay board directly to the arduino’s vcc and GND. i didnt really understand LarryD’s schematic that much. i tried following the picture below, but once again it did not work.

If that is the relay board you have, I believe you have to connect JD-VCC to VCC.

EDIT: IN1 2 3 etc. go to the Arduino o/p pins.

You need your grounds of each board hooked together. Otherwise, if you send a signal from arduino to the relay board, it has no reference for the voltage sent. The common grounds, give a common reference.

Thanks for all the advises!!!! project is a success =)