Note: The Collector-emitter voltage can be set up to a maximum of 30V. Whereas, when the LED is provided with a logic 1, LED will turn on and trigger the transistor and shorts the collector-emitter junction and we will receive a 0 at the output. Working: When the IR LED is provided with a logic 0 input the LED will be in OFF condition and will not trigger the transistor and the output we will receive is a HIGH across the collector-emitter terminal. Note: Do not connect the emitter and the cathode pin to the same ground as they are meant to be isolated. The emitter pin(pin 4) is to be grounded.

Here for our case, we have connected an output probe to monitor the output. The collector pin(pin 5) is pulled up using a resistor and the output device is connected to the other end. The infrared LEDs anode(pin1) and cathode(pin 2) pins are to be connected to the logic input and the ground, respectively. The working circuit below can be followed to design your own circuit and get the optocoupler IC to use. To use the IC as a phototransistor we will not be needing the base pin(pin 6). The optocoupler IC consists of gallium arsenide infrared LED and a silicon NPN phototransistor and using the IC is also pretty easy.

The table below can be referred to understand the pin configuration of the IC. The IC comes as a dual inline package and has 6 pins. Note: More technical information can be found in the 4N35 Datasheet, linked at the bottom of this page.

Operating Temperature: -55 to 100 Degree C.

This section mentions some of the important features and specifications of the optocoupler IC.

Opto isolator circuits