I'm having trouble with a set of relays that I bought. It is the small set that only has the two relays on the board. http://www.sainsmart.com/relay/arduino-pro-mini.html
I've tried wiring them every way imaginable and they still won't work properly. The only way they will come on at all, is if I put my 5 VDC to the VCC terminal, and they will not actuate with the outputs from the controller. I've tried them with two different Arduino Uno's. I'm also not sure which is the proper placement for the jumper. I'm not sure what I'm doing wrong. Any help would be most appreciated.