An intelligent infrared remote control switch of theory and design (1)

0 introduction

Infrared remote control is currently using the most widely used means of communication and control, because of its simple structure, small size, low power consumption, strong anti-interference ability, high reliability and low cost and widely used in home appliances, industrial control and intelligent instrument system.

However the vast majority of remote on the market are designed for their specific remote control object design and cannot be directly applied to common smart device development and a more general control applications. Typically, most families are using TV, air conditioning, VCD/DVD, and other household appliances are using an infrared remote control, infrared remote control device for the respective product designs, resulting in a general family owned several remote control, you can use these remote control function for reuse, thereby reducing the number of the remote control, remote control more powerful, it is very necessary.

Power switch is widely used in homes, factories, warehouses, as well as offices and other places.

The traditional mechanical power switch exists contact resistance, easy to wear, low reliability and life expectancy is short, and so on shortcomings, especially when the remote control of home appliances, if you can use these remote control design switch is used to replace the traditional mechanical power switch not only cost savings, and the ease of operation. The use of television sets, home appliances of remote control switch operation, installation and substitution are very convenient, it can be used very popular in the substitution of household wall switch, thereby improving the the remote control in home appliance fields of practical value.

1 works

Infrared remote control switch is mainly composed of infrared receiving, zoom in plastic, microcontrollers, switch control, and buck power modules, its principle diagram shown in Figure 1.

Infrared remote control switches feature is the remote control for the common household appliances such as televisions, VCD/DVD, etc, either by the user to specify a key for the infrared remote control switch control keys.

Use when the user presses the intelligent infrared remote control switch of "learn" button, and then on the remote control switch of infrared receiving head press this switch is specified on the control button and an infrared remote control codes signal after receiving IR receiver, after zooming in plastic, enter into a micro-controller, micro-controller with built-in remote control for the specified E2PROM remember the key of encoding. Then, when the user next time, when you press the remote control to the specified key, the infrared code signal same through infrared receiving head, enlarge after plastic surgery to microcontrollers, entered by the micro-controller issued a control signal control switch control module inside the relay on and off, turn on/off control of output voltage.

In order to ensure the realization of various electric remote control switch control, the control signal to stability and security.

To this end, during the transfer process to enable communication between the various module signal is strong enough, this requires the circuit power to independent power supply parts to the circuit. Therefore, infrared remote control switch must also have step-down power supply module.

2 circuit design

Hardware circuit design including power circuit design and decoding circuit design in two parts.

Power supply circuits for decoding circuit designed to provide power, in addition to the required voltage stability, also called for its small size, low cost. Decoding circuit requirements can infrared codes reliably received, at the same time be able to stably control relay switch.

2.1 power supply design

Taking into account the power consumption of the decoder is very small, so the power of design uses capacitance buck power.

It's worse than a transformer power supply and switch on the power of design to be simple and small size, low cost, suitable as a remote control switch of the power supply. Power supply design schematic diagram shown in Figure 2. MC2 buck capacitors, D1 as half-wave rectifier diode D2 in the city of negative half week to provide discharge circuit, MC2 ZD1 5.1 V Zener diode, R1 to shut off the power after MC2 charge discharge resistance.

Capacitance buck power is the use of capacitance at AC signal frequencies produced by the capacitance to limit the maximum operating current.

When the AC voltage is 220 V, frequency 50 Hz work conditions, the capacitor MC2 in circuit capacitance Xc (Ω):

Through capacitor charging current MC2 Ic (mA):

By buck capacitance MC2 for current to the load is actually flowing through Io MC2 and sufficient discharge current IC.

Obviously, the larger the MC2 capacity capacitor capacitance Xc smaller, then flows through the MC2 and sufficient, discharge current. When the load current Io is less than the charge and discharge current of MC2, extra current can flow through the regulator hose. If the voltage of the maximum allowable current Idmax < IC-Io easily cause voltage tube when burned.

Although the current flows through the capacitance MC2 IC 69.08 mA, but almost in capacitors does not have power, this is because an ideal capacitors, capacitor current to flow through the imaginary part of current, it's work for reactive power.

Visible, capacitance buck power supply with high efficiency. After the test, the power supply circuit after power output 4.88 V DC voltage to AC voltage component is less than 3 mV, output current at 50 mA, voltage 4.7 V, can meet the decoding circuit power requirements.

2.2 decoding circuit design

Infrared remote control switch hardware core part is the micro-controller and infrared receiver section, the schematic diagram shown in Figure 3.

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