Infrared receiver made with CD4040

With the popularity of home appliances, people have many infrared remote controls. They use the infrared signals they emit to control the functions of home appliances. This work can receive the infrared signals emitted by the infrared remote control and display them with lights.
1. Infrared receiver circuit

This circuit uses an integrated infrared receiving tube (head), which greatly simplifies the circuit. The circuit diagram is shown in the figure below.
2. Circuit Principle
The circuit includes two parts: infrared reception and signal display. The infrared receiving head tube used in the circuit is an integrated circuit, which includes infrared receiving diodes, amplification, frequency selection, demodulation and other parts. When it receives the modulated infrared signal emitted by the infrared remote control, it directly outputs the control signal of the appliance at the output end after receiving, amplifying and demodulating it. There are many models on the market (such as SFF-"1506-38, TL1838, etc.). It integrates the infrared receiving tube and the amplifier circuit into one, and its size is equivalent to that of a medium-power triode, with good sealing and high sensitivity. It has three pins, namely the positive pole of the power supply, the negative pole of the power supply and the signal output end, and the working voltage is about 5V. The pin wiring diagram of the infrared receiving tube TLl838 is shown in the figure on the right.

The control signal output by the infrared receiving head is connected to the CP terminal of the CD4040 counter. The 4040 can calculate the number of pulses of the control signal, and then display it by the light-emitting diode connected to the output terminal. Since a control command signal contains hundreds of pulses, the 12-bit counter only uses 8 bits (Q1~Q8) to effectively display the result.