Hi all. I have arduino uno and relay 8 roads 12v from LC Technology, and for some reason it's doesn't work. Main thing in that it worked from beginning, but stopped for some reason. Maybe I connected it wrong? Can someone give me a scheme of the connection? Or maybe some advice?
Hi, can you post your code and a circuit diagram, either CAD or picture of hand drawn circuit in jpg, png or pdf format.
A picture of your project would also help.
What the spec or link to your 8 relay PCB, at the moment we have no info on your project, so we have no way of commenting on how to fix your problem.
Before posting your reply please read this link.
http://forum.arduino.cc/index.php/topic,148850.0.html
It will show you how to post code and pictures.
Hope to help.
Tom..... 
Welcome to the forum.
it would be helpful if you posted a link to the part as the data sheet will help.
if this is like other 8 pin relays, you would need to supply voltage onto the logic input pin. the arduino pins would then bring the logic level to ground.
for the one and two relay boards, it is inportant to connect ground as the arduino pins have to supply the 5volts.
so, make sure your relay board has the 12 volts it needs for the relays, has a ground in common with the arduino and that there is a power supply connected to the logic voltage input.
if you are using 12 volt on the logic side, you must choose your dropping resistor accordingly. if you have a spare 5 volt supply, that might be safer. the optoisolator can be thought of as a 10mA LED so you can use that for your calculations.
best to double check the schematic and data sheet.
Here is code of test scetch (it's just for make relay work):
#include <Wire.h>
#include <AFSoftSerial.h>
void setup () {
pinMode(4,OUTPUT);
digitalWrite(4,LOW);
}
void loop(){
}
https://docs.google.com/file/d/0BxkYJF0YZNHbYlF3QzRYLWRhcFU/edit?usp=docslist_api