IR Emitter LED 940nm 5mm (5-Pack)

For IR remote control or IR obstacle and intrusion sensors.

DESCRIPTION

These infrared emitting LEDs operate at 940nm and used for creating IR remote control or IR obstacle and intrusion sensors.

PACKAGE INCLUDES:

• IR Emitter LED 940nm 5mm  (5-Pack)

KEY FEATURES OF IR EMITTER LED:

• 940nm nominal wavelength
• 3.3 and 5V compatible

Infrared is the light spectrum up around 940 nm that is commonly used for IR remotes and is outside the visible spectrum for the human eye.

These devices are very useful for adding IR capability to a project including everything from making a custom IR remote for your TV to creating a custom serial IR communication link for a robot project or to make an intrusion detector if the IR signal is blocked.

If you need a receiver for use with the transmitter, you may also want to pick up our IR phototransistor or IR receiver module at the bottom of the page.

The LED is easy to use and similar to normal LEDs in operation.  Connect the cathode lead to ground and drive the anode lead with a logic high to turn on the LED.  As with any LED, a current limiting series resistor is needed to protect the LED and/or the device being used to drive it.

The LED has a forward voltage drop of 1.2 to 1.4V.  If driving it off a 5V MCU, a resistor value of 120 ohms will limit the current to a level of about 30mA.  This is typically safe when pulsing the LED as is typically done in most applications.  If driving the LED constantly on with an MCU, keeping the current down under 20mA is generally required depending on the MCU being used.

Since IR light is not visible to the human eye, it will appear that the LED is doing nothing so you will need something that is sensitive to IR light to detect that the LED is actually operating.  For a quick check, the camera on a cell phone is more sensitive to IR light, so if you view the LED through your phone camera, you should be able to see it operating.  You can of course also use something like our IR Receiver module for detecting the IR as well.

Calculating LED Resistor Values

For remote control applications, the IR is typically pulsed at a modulated rate of 38kHz to created coded messages.  Different manufacturers have different transmission protocols for these coded messages.  There is a library that can be used with Arduino called IRRemote if you are looking to create a remote control application.

The IR emitter can also be used as part of an emitter / detector pair where an object is detected if it breaks the beam between the two.  In this case, the IR emitter is usually driven on all the time rather than being pulsed.

OUR EVALUATION RESULTS:

IR LEDs can typically be driven harder than standard LEDs.  We have tested these LEDs at continuous operation at 50mA without any issues and so they should be safe to use in pulse mode up to 100ma.  If using directly with a uC, the current should be limited to about 30mA to avoid damage to the microcontroller.

The circuit below is an easy way to setup a simple IR emitter / IR phototransistor pair to experiment with basic operation.  When the IR phototransistor detects IR from the IR LED, it will turn on and light the IR Detected LED.  The brightness of the LED will depend on the strength of the IR that is detected.  IR detector components are available below.

Note:  If the IR Detected LED only glows slightly, make sure that the IR Phototransistor leads are not reversed.

Notes: 

1. None

TECHNICAL SPECIFICATIONS

FURTHER READING

Determining LED Current Limiting Resistor Values