Electronic schematics, circuit designs
Wireless headphones transmitter circuit schematic
This wireless headphones transmitter assures a quality reception over 2 meters. The oscillator frequency is between 1750KHz and 3500KHz and for antenna we use a ferrite bar. IC1 amplifies the audio signal and TC1 is a buffer. D1 signals that the transmitter is on and is a voltage stabilizer for the oscillator .
L1 is a toroidal core T50-2 with 80 turns, 0.2mm Ø. L2 requires a 10-20cm ferrite bar, L2a has 3 turns, 0.6mm Ø coiled at ground end of L2b wich has 30 turns, 0.5mm Ø .
The current consumption of the wireless transmitter is <= 150mA and is to be used with this wireless headphones receiver.
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Wireless headphones receiver circuit schematic
The wireless headphones receiver presented is an standard application of ZN415 produced by Ferranti ( short wave receiver ). ZN415 assures a quality reproduction, has a 1.5 battery alimentation and contains a MA detector and audio amplifier.
The current consumption is < 5mA, L1 has 40 turns, 0.2 Ø copper and 20mm Ø ferrite. C1 is adjuted with an non metal screw, the reception frequency of this wireless headphone receiver is between 1.7MHz and 3.4MHz - shortwave receiver.
This wireless receiver is to be used with this wireless headphones transmitter.
4 channels mixer voltage controlled
The audio mixer schematic we propose is developed arround 4 amplifiers build inside SSM2024 produced by Precision Monolithics Inc. (PMI) and is voltage controlled (VR).
The maximum VR voltage is 5.5V. The signal/noise ratio is 90dB and 130Khz band wide. This 4 channels mixer works great at +- 15V but you can use voltages between 9V and 18V.
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