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Topic: Wiring a Opto-Isolated Relay to Arduino (Read 3549 times) previous topic - next topic

Existence

Hi, I was wondering if someone could help me interpret the instructions to wire up the following Opto-Isolated Relay (http://arduino-direct.com/sunshop/index.php?l=product_detail&p=156)

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NOTES: If you want complete optical isolation, connect "Vcc" to Arduino +5 volts but do NOT connect Arduino Ground.  Remove the Vcc to JD-Vcc jumper. Connect a separate +5 supply to "JD-Vcc" and board Gnd. This will supply power to the transistor drivers and relay coils.


So I understand the first part I connect 5v to the device. The second part has me confused though. I have a 5V wallwart so I connect the +5 to JD-VCC does that mean I connect the neutral off the wallwart to board ground? Or do I just ground that pin to the case?

I'm just a beginner as you can tell so go easy on me if it's a silly question  :)

Thanks

CrossRoads

If you want complete isolation,  you will have seperate 5V supplies, one for the Arduino and one for the relay power.

Then you would connect an arduino output pin to the cathode of the drive LED, with VCC to a current limit resistor to that anode.

On the other side, you have pin 1 of the jumper field goes to the pin that goes to Pin 4 of the optoisolator.

If you  only have 1 wallwart, leave the jumper in. Having an optoisolatar and the relay seems like overkill to me. Most applications just drive the transistor to drive the relay.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Existence

Thanks for the reply, I have two wall-warts but i'm still having a hard time following you. I quickly put this diagram to together to better help me understand (Don't laugh I only had paint).

Grumpy_Mike

Not sure what the optoisolated relay is can you give a link. What you drew is not what anyone was expecting.
You need a ground going from the arduino into that optoisolated relay, I am not sure I understand what the right hand connectors are, and where is the load you are trying to drive with the relay?
Is it a mechanical relay or a solid state one?


Grumpy_Mike

OK that is a rather unusual design you have it right apart from the 5V wall wart the positive output should be connected to the Vcc not the JD-Vcc

CrossRoads

Mike,
Having the seperate 5V go to the JD-Vcc means the Opto-receiver and the Relay are totally isolated from the Arduino Vcc.
Overkill for sure, but the design provides for that.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Existence

Makes sense now, appreciate the help guys.

Existence

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Having the seperate 5V go to the JD-Vcc means the Opto-receiver and the Relay are totally isolated from the Arduino Vcc.
Overkill for sure, but the design provides for that.


I'm just trying to understand this a bit better. Since I'm not tying the grounds together does that mean the second wall wart is acting like ground for the +5v coming from Arduino? Or is it grounding through the Input PINS? I updated the pic as the last one was a bit confusing.

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