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Description Using this low cost Project one can reproduce AUDIO from TV without disturbing anyone. It does not use any wire between TV and HEADPHONE. In place of pair of wires it uses invisible Infrared light to transmit audio signals from TV to Headphone. Without using any lens a range of up to 6 meters is possible. Range can be extended by using Lenses and Reflectors with IR sensors comprising transmitters and receivers. IR transmitter uses two-stage transistor amplifier to drive two IR leds connected in series. An audio output transformer is used (in reverse) to couple Audio output from TV to the IR transmitter. Transistors (BC547) & (BD140) amplify the audio signals received from TV through audio transformer low impedance output windings (lower gauge or thicker wire) are used for connection to TV side while high impedance are connected to the IR transmitter. This IR transmitter can be powered by 9v mains Adaptor or 9v Battery. Led in transmitter circuit functions as power-on in...

This long-range cordless burglar alarm circuit makes use of a cordless telephone (CLT) unit with paging facility and a few low-cost discrete components. The circuit is so simple that even a novice can easily construct it without any difficulty. When the ‘page’ button on a CLT is pressed and held in that position, the handset starts beeping to indicate that somebody is calling. This function is used here to build the gadget. The system consists of three sub-assemblies:      1. Wireless beeper. The handset of the CLT. 2. Infrared transmitter. A number of IR transmitter circuits based on the well-known 555 chip have been published earlier in EFY. Just select one circuit with a modulating frequency of 36 to 38 kHz and assemble it on a veroboard. After that, enclose it in a proper cabinet. (EFY note. A typical IR transmitter circuit used during testing is shown in Fig. 1.)   3. Infrared receiver-cum-control unit. The circuit diagram of this unit is shown in Fig. 2. Front end of this bloc...