The transmitter is intended primarily for use with the receiver in the preceding articles. It works form two small 1.5 V dry batteries or one 3 V lithium battery. To make the unit compact and yet have reasonable frequency stability, the design uses a phase shift oscillator, T1, which provides good frequency stability. To ensure[…]
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Infra-red transmitter
Infra-red transmitter: It often happens that someone wants to watch television without the sound disturbing other people in the room. To avoid having a long cable trailing over the floor, the present transmitter (and accompanying receiver ) make it possible to listen to the TV sound wirelessly. The transmitter uses pulse-duration (=pulse-width) modulation. The modulated[…]
Read moreFerguson BSB receiver as D2MAC decoder
After the demise of BSB( British Satellite Broadcasting) in early 1991, the electronic surplus market was flooded with the tens of thousands of brand new but otherwise unusable satellite TV indoor units plus 55-cm dish antenna or squarials. Initially, unmodified ex-BSB sets went at giving away prices of £20 and less, which is the fraction[…]
Read morePLL synthesizer for TV receivers
Modern TV tuners normally contain means to scale down the VCO (voltage-controlled oscillator) signal. The one used in the proposed synthesizer is a Philips Type UV816/6456, whose scale factor can be set to 64 or 256. It operates over the low VHF band, the high VHF and hyperbands, and the UHF band. The proposed circuit[…]
Read moreInfra-red headphone receiver
Infra-red headphone receiver: This receiver is meant to complement the transmitter describe in the previous article. Its design is based on just one FET. This has the advantage that construction is simplicity ‘itself, and the disadvantage that for a sufficiently low output impedance the value of drain resistor R3 has to be fairly low. That results with[…]
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Infrared signal repeater circuit diagram
Purpose of Infrared signal repeater: The infrared signal repeater is intended to extend the operating range of a standard Infra-red (IR) remote control system used with an audio or video system to around 10 meters (33 ft.). The original signal is picked up by the receiver (Fig. 1), amplified and then fed to the transmitter[…]
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Infrared Headphone Receiver Circuit Diagram
Purpose and design of Infrared headphone receiver: This receiver is meant to complement the IR headphone transmitter. Its design is based on just one FET. This has the advantage that construction is simplicity itself, and the disadvantage that for sufficiently low output impedance the value of drain resistor R3 has to be fairly low. That[…]
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Infra-red Headphone Transmitter Circuit Diagram
Purpose of Infra-red headphone transmitter: The proposed transmitter provides an optical (infra-red) that is wireless, connection to a headphone. Three infra-red (IR) LEDs are provided with a quiescent current by T1. The level of that current is set with P1. When an audio signal is applied to the gate of T1, the current through the[…]
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