I recently bought this optoisolator (datasheet PDF). I am wondering how I can connect it to my Arduino. I have some ideas, but I am afraid to test them because I might damage the board.

What I am trying to do is to connect and disconnect a circuit. What should I connect to the pins on the breakout board? The pins are labeled:

  • OUT1
  • HV
  • OUT2
  • HVG
  • NC
  • IN1
  • IN2
  • GND

and the schematic is here.

  • 1
    \$\begingroup\$ Just to note it's usually better to wait a while before accepting an answer (e.g. wait a few hours to see what turns up - you may get a better answer) Some folk may not bother answering if they see an answer has already been accepted. \$\endgroup\$
    – Oli Glaser
    Feb 6, 2012 at 18:42
  • 2
    \$\begingroup\$ This question is related to 'Trigger old camera flash', but this one seems to be interested in the connections to the Arduino, while the other is more about the connections to the circuit to be added (a camera flash). (BTW, it contained similar grammatical errors, I corrected them in both places. Please make an effort to improve the quality of your posts before adding more!) \$\endgroup\$ Feb 6, 2012 at 18:56

2 Answers 2


According to the schematic, there are current limiting resistors in place (R1 and R2) so you can just connect your Arduinos outputs directly to IN1 and IN2, and it's ground to GND.

The rest of the connections are for the isolated side (marked "noisy system" in the schematic) so you connect your separate power supply (the one you want isolated from the Arduino) to HV (V+), and HVG (ground - not the same ground as Arduino) and the signals come from OUT1 and OUT2. If your isolated supply is e.g +15V, then your signals will be from ~0V min to +15V max (assuming digital signals)

  • \$\begingroup\$ the device i am trying to power has 2 wires if i connect them the device starts if i put one in HVG and one in HV how can i then start the device ? sorry for this n00b question \$\endgroup\$
    – opc0de
    Feb 6, 2012 at 15:20
  • \$\begingroup\$ You run the power to your (isolated) device V+ and 0V, and also to HV (device V+) and HVG (device 0v) in order to power the ouput transistors. If you are talking about switching the devices power on/off from the Arduino, then update your question with details on the device (voltage/current ratings, etc) and exactly what you want to achieve. \$\endgroup\$
    – Oli Glaser
    Feb 6, 2012 at 16:14

Assuming that your device outputs a voltage, which you want to read using the Arduino:

  • HV-GND == Arduino GND
  • HV == Arduino +5V
  • OUT1 == Arduino input pin
  • GND == device ground
  • IN1 == device signal (assuming 0V for low and +5V for high)
  • \$\begingroup\$ Ah, I was assuming he wanted to do things the other way round (Arduino outputs signal to device) The board description seems to indicate this is the intention with the mention of a low voltage side controlling a high voltage side, and the HV and HVG being for "high-voltage" and "high-voltage-ground" I think. Of course there is no reason why you couldn't use it the other way round though - it might be useful if @opcode clarifies which way the signal is being sent. \$\endgroup\$
    – Oli Glaser
    Feb 6, 2012 at 18:39
  • \$\begingroup\$ You already answered the output version, I added the input version. @opcode accepts yours, so I hope (for him) he indeed wants to use it as output. \$\endgroup\$ Feb 6, 2012 at 22:38

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