Careful!! The sample schematic shows a 50 ohm resistor in series with the LED. This is WAY too little for an Arduino I/O. 220 ohms or more would be OK.
The specsheet shows the 50 ohms for testing speed with a signal generator, it's NOT for general application.

Does it matter that your schematic differs from the datasheet? I always thought that the emitter of an NPN transistor always was connected to ground. Like in the datahseet, this would give an inverted output to the input signal. Since this device does not have an external base to drive, will it work (or has it been tested) with the schematic posted with this part?
Thanks in advance.

I used this in a very simple circuit to control a dSLR camera via wired remote. (@sparkplug781, I think it did match their exaple schematic.) The project was to generate a slow-motion video of a camera's shutter action.

I have the circuit working fine, although the example schematic has the pinout backwards for 3/4. And the example schematic lists it as a diode diode OI, when according to the datasheet it is a Diode photo transistor OI. This is a large difference in performance as this variety can really only reliably generate square wave outputs and diode diode can transfer most signal-functions.

1.) Can anyone tell me why I didn't get signal through the OI until I used a fairly large resistor on the voltage divider (~50K)? The example circuit has a 50 Ohm listed. Virtually any resistor should work since it is 0-drop voltage divider. I imagine if the source V has any capacitance you will inadvertently create a high-pass filter; but I don't think that is what is occurring here. I put a 100K trim pot and was able to tweak in good square waves at 40K

2.) It isn't listed anywhere, but like any LED you will need a >~1.5V input voltage to trigger any signal at all, R1 (input) should be matched like any LED resistor depending on Vin.

Just curious, what is the difference between this and a solid state relay?

In case this info helps anyone else, this SparkFun optoisolator (COM-00314) (Lite-On LTV-816) is reliably transmitting 19200 baud serial data between my embedded Arduino (ATmega328P) and SparkFun's FTDI Basic (DEV-09716). The embedded Arduino receives commands over an nRF24L01+ link and writes some debug statements to serial while it evaluates the commands and takes appropriate action. The optoisolator allows the Arduino project to remain powered by its power supply and let me view the debug statements in the Arduino IDE serial monitor without worrying if my homebrew Arduino power supply will damage my spiffy laptop through the USB path.

Next step is to move the optoisolators and requisite resistors to a li'l PCB with headers so it can snap onto the FTDI Basic when needed. Different models might get faster baud but 19200 is the fastest I could get. YMMV. Hopefully that helps you in your projects.

Can any one confirm if this is the surface mounted or though hole version? The spec sheet is for a surface mounted version (LTV-816S), however the photo appears to show a through hole design (LTV-816).

Can this be used to read a high voltage/noisy signal into the MCU? For instance, Pin 1 is the noisy high voltage signal, Pin 2 ground. Pin3 3.3v from MCU and Pin 4 is digital read pin on the MCU.

Thanks!

is there a specific reason why the data sheet shows only a single NPN transistor in this product? why is the datasheet showing a different IC? is the example schematic what I should rely on?

Can this be used to read large loads, for example I'm currently using 120v relays to read when a switch is on by an arduino.

Could this be used to convert 24V AC to 5V DC?

good pricing for such a product, but when will it be back in stock? also does anyone know of an equivalent SMT version of this?