Optoisolator - 1 Channel

This is an opto-isolator for controlling large loads of current on a single channel. This 4-pin dip can be used in conjunction with relays, small motors, etc. to allow a simple microcontroller to turn on and off up to 50mA.

  • [ Datasheet](http://cdn.sparkfun.com/datasheets/Components/General IC/LTV-816S.pdf)
  • Example Schematic

Optoisolator - 1 Channel Product Help and Resources

Core Skill: Soldering

This skill defines how difficult the soldering is on a particular product. It might be a couple simple solder joints, or require special reflow tools.

2 Soldering

Skill Level: Rookie - The number of pins increases, and you will have to determine polarity of components and some of the components might be a bit trickier or close together. You might need solder wick or flux.
See all skill levels

Core Skill: Programming

If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.

2 Programming

Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
See all skill levels

Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

3 Electrical Prototyping

Skill Level: Competent - You will be required to reference a datasheet or schematic to know how to use a component. Your knowledge of a datasheet will only require basic features like power requirements, pinouts, or communications type. Also, you may need a power supply that?s greater than 12V or more than 1A worth of current.
See all skill levels


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • 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.


  • 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?

    • Technically, yes - IF you put it it a circuit designed for such a purpose. This component by itself will not do the job, but it will isolate one circuit from another with each side potentially operating at different Vcc values. I would recommend using a diode and capacitor on the AC side to rectify things to a somewhat choppy DC voltage which could then be fed to the LED side of this part. You would still need an independent 5v supply on the transistor side to detect changes in the AC input (actually, that's exactly how I'm currently thinking of using this part).

    • No, sorry this used to control higher mA loads not convert voltages.

  • 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?

Customer Reviews

No reviews yet.