Remote control of light and fans basics

Introduction:- Home automation is very interesting project idea  now a days in electronics. To control any light or fan by remote control we have to use relays in addition to switch. The light can be control by relay only or relay and switch depends on wiring of relay/switch. To control light with both switch and relay we need two way switch and a relay with change over contact.

Basics of remote control:- There are mainly two parts first is hand held remote control unit and other is receiver unit. These remote works for a distance of 10 feet's normally. remote control has a set of push buttons to give on off commands. The signal from remote is sent to receiver by radio waves/ infrared waves or blue tooth system. TV remote uses infrared signals. Small toys car/drones uses radio waves. DTMF signal is also used in some system where more items (channel) are controlled. In case of blue tooth control we can use mobile phone as a remote control with some remote apps. So on the basis of medium of signal sending remote control can be of following types

1. Infrared remote control:-  uses infra red rays as medium.
2. Radio frequency remote control:- it uses radio frequency as carrier for signal. Blue tooth also uses radio frequency. 27 MHz trans receiver modules are also available for remote control.
3. Mobile SMS based:- this system uses a GSM mobile module with a sim card. With mobile phone SMS is sent to Gsm module. This message is decoded by arduino microcontroller and operate different relays to control appliances.

Main steps in working

1. Push buttons / switches:- we can use single button/switch to on/off a light or two button separately for on and off operation. To control 4 light we need 4 button in first system and need 8 button in second system.

2.  Coding button signal:- The 5v signal from button goes to coding IC which generate a digital signal corresponding to that button.

3. Oscillator circuit:- this circuit generate a high frequency carrier wave.

4 Modulation:- the digital signal received from IC is mixed with this carrier wave. This modulated signal is amplified and given to small loop aerial.

5. Receiver unit:- the signal received by receiver unit is amplified and demodulated to separate the digital signal sent by remote control. This digital signal is decoded in decoder IC, which gives output on a corresponding pin. This signal is used to picks up a relay. The contact of relay is closes and makes light on. The remote control has same number of relays as number of channel to control.

Note above is a general description but different remote control may use some what different logics for control.




main-sections-of-lcd-tv