Simplest Wireless Headphone

Simplest Wireless Headphone
A basic Infra Red Link for audio communication for distances up to 10 feet.

Working
The transmitter comprises a single amplifying stage driving two series connected IR LEDS. The input source is connected to J1. Please note that the device will pass a small DC current through it and also directly bias the transistor. A suitable device is therefore a high output crystal microphone. These can produce high output voltages up to 1 Volt but this will be reduced by the transistors low input impedance.

The receiver is three stages, the first stage being a photo-transistor. Stages two and three form a high gain darling-ton emitter follower, the bias for the whole stage derived through R2 and the photo-transistor itself. C1 and R3 form a filter to reduce interference from fluorescent lighting and other hum sources. The output is via Jack J2. Note also that the output device will pass a small DC current so a medium impedance loudspeaker or headphones are a good choice here.

Circuit Diagram


NOTE : Click the diagram for better Quality.

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