I could use help understanding this relay board

I am trying to understand how I would use this relay board: http://www.ebay.com/itm/2-Channel-12V-Relay-Module-With-Optocoupler-For-Arduino-DSP-AVR-PIC-ARM-/321151393125?pt=LH_DefaultDomain_0&hash=item4ac61d5d65

I would think i would just puyt the arduino's ground on gnd and then set one of those pins labeled in1 and/or in2 high to trigger the relays, but then the schematic confused me. If someone here understands how this relay board works and how I would wire it up(just the arduino side) that would be very helpful.

Thank you!

Arduino +5V on VCC Arduino GND on GND Arduino o/ps on Realy card i/ps

Relay card LEDs are shown backwards.

thank you, that makes sense. And then do I put 12v across it where it says "jd-vcc", "vcc" and gnd? Also would it be better/easier to use that 12v relay with its power coming from a 12v battery or this 5v relay http://www.ebay.com/itm/2-Channel-5V-Relay-Module-With-Optocoupler-For-Arduino-DSP-AVR-PIC-ARM-/221248889308?pt=LH_DefaultDomain_0&hash=item33837621dc getting power from the arduino. (this is going on a motorcycle if that makes a difference)

http://www.ebay.com/itm/2-Channel-5V-Relay-Module-With-Optocoupler-For-Arduino-DSP-AVR-PIC-ARM-/221248889308?pt=LH_DefaultDomain_0&hash=item33837621dc You have it.

And then do I put 12v across it where it says "jd-vcc", "vcc" and gnd?

5 volts if you use the LINK you gave. These are 5 volt relays ~100 ohms (5/100=50mA for the coil). Get 5V from Arduino.

EDIT: However if you are using the Arduino to power other things, using a 12V board would save you 100mA if both relays were energized.

I ordered the 8-relay version no too long ago. These boards are really nice, but it did confuse me at first too.

If you supply your arduino with 5v directly, just supply this board to the Vcc pin the same way. Otherwise like LarryD said, from the +5v on the arduino to the Vcc pin on the relayboard. Connect Arduino GND to any of the relay GND (or connect relay GND to - on your 5v supply if you are using one)

It's just like you said, and like LarryD said. You can either connect everything to the arduino, or just the outputs like I did.

This is how I ended up hooking up my digispark to it: https://docs.google.com/drawings/d/1LRfwtz8sct8Hm08lqeQ6B93HI6pUo5tBVU7Jr4_pQUk/edit?usp=sharing I put it upside down on the pins, to get the order right. That's why the outputs are crossed :P

Then just control the relays with high/low.

You don't need to put anything at the gnd/vcc/JDvcc. the GNDs are connected internally, so is the Vcc. The jumper is used so that Vcc is powering the Relays (JDVcc goes to the relays). They are 5v relays tho, so no need to use anything else than 5v.

So if you are using a 12v battery, I guess you should connect that to the Arduino VIN and then power the relay from the +5V pin on the arduino.

Thank you both!!! Very helpful and informative! XD

So I got this board and set it up, but I have a problem. Or at least I think I do. When I run my program I can clearly hear and feel at least one of the relays switching, but when I test the connection with a multimeter it shows there is no connection. Could the board I got be faulty? It also appears that only one relay is working. I have it wired as so: Board Gnd to Arduino GND Board VCC to Arduino 5V Board In1 to Arduino Pin 10 Board In2 to Arduino Pin 11 As far as the code it appears that the relays activate when I set the pins low(which doesn't seem right, but maybe it is) and i only hear a click when I set pin 10 low not pin 11.

Nevermind. I believe one relay on the board is faulty, other than that it all works as expected.