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Controlling devices using switches are common. From a few decades controlling devices using remote control switches like infrared remote control switch, wireless remote control switches, light activated switches are becoming popular. But these technologies have their own limitations. Laser beams are harmful to mankind.

Our DTMF decoder can be powered from a 9V battery or from your parallel printer port. It can detect and display all 16 DTMF digits on your computer screen in real-time. The Window's program can be placed in the minimize mode and still detect tones while you use your computer to do other things like Net surfing!!!! We are now in the process of adding an DTMF decoder which will interface to the sound card gameport

The tone generator (top) uses the 5589 chip and a DIP switch. You can actually hear the tones through the speaker. The bottom circuit uses the 8870 to decode a tone and display its associated number on the 7-segment LED. This tutorial will not discuss telephone interfacing. Rather it will give you a basic working foundation which you can build upon. The generator/decoder above are tethered together by a single wire. But you can expand upon this foundation for wireless remote control using a microphone. For longer distances maybe you can add a pair of walkie-talkies, generating audible tones into one, and decoding with the other. Another possibility is to use infrared (IR). Since tones are just electrical pulses, you can replace the speaker with an IR emitter and add an IR detector to the decoder.

H ere is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances. This remote control unit has 4 channels which can be easily extended to 12. This circuit differs from similar circuits in view of its simplicity and a totally different concept of generating the control signals. Usually remote control circuits make use of infrared light to transmit control signals.

Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 is an 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need to test this IC separately. A quick testing of this IC could save a lot of time in research labs and manufacturing industries of communication instruments. Here’s a small and handy tester circuit for the DTMF IC.

This is a single channel (on / off) universal switch that may be used with any Infra Red remote control that uses wavelengths between 850-950nm.

This is the project of infrared vision system for a toy car. It will project 2 modulated IR beams ahead and detect any reflection of these beams on any obstacle ahead of the car. The circuit will then invert the car's motor for a given time thus changing the direction of advance as it goes in reverse. No special control for steering is necessary as the car has the front wheels' shaft in an eccentric support: when going forward it auto aligns itself, when running backwards the shaft turns and the car describes a curve.

The encoder/decoder parts are to be connected to a transmitter/receiver module which takes care of the transmission of digital signals by radio or infra waves. The communication signal format is designed to be used for radio transmission (it has a constant 50% signal/silence ratio), but it can work with infrared devices as well.

This little project will demonstrate how you can use NEC IR protocol based TV, DVD or VCR remote control to control you home appliances like fan bulb or virtually anything. There are lots of projects out there to accomplish this task but i have to write my own code because of too many requests on IR infrared Remote Control Relay Board with PIC12F675 Microcontroller. There are a number of consumer Infrared protocols out there and they have been used for every single purpose possible, like PDA laptops and other consumer appliances. RC-5 & RC-6 by Phillips, RCA are few examples of consumer IR protocols.

This is a true 'minimalist' remote, having but three functions: Volume Up, Volume Down and Mute Volume is controlled by a motorized (motorized for US readers) pot rather than any of the 'digital' pots that now abound, and this was done for a number of very good reasons.