Infrared LED Diode Activated Transistor Switching and Relay Circuit

This is a demonstration of an infrared LED diode transmitter and receiver. Infrared signals are not visible to the naked eye and it comes below the visible or light range of frequencies. It has two parts, 1) the transmitter that consists of an infrared emitting LED diode and 2) the receiver which consists of an infrared receiver diode.
The transmitter has an infrared emitting diode which emits or transmits infrared signals. The infrared emitting diode is powered by a 9 volt battery through a series 680 ohm resistor. The infrared transmitter LED diode emits infrared signals. It converts electrical energy into signals in the infrared frequency range.
The receiver consists of an infrared receiver diode, which receives the emitted infrared light from the transmitter and converts it into electrical signals. The electrical signal is then connected to the base circuit of a small signal transistor, which makes the transistor to turn on according to the signal voltage. This transistor switches another power transistor that is connected to a load such as a motor, a buzzer, an alarm or a relay.
This is a simple circuit that anybody can make.