Wednesday, August 4, 2010

Ultra- miniature Transmitter

This transmitter has a size about  that of a large coat button.The transmitter accepts direct voice input and work on a single watch type button cell that serves several tens of hours together.As shown in schematic the transmitter is probably the simplest one ever designed.A single transistor, a few passive components and a small carbon button mike do the trick.

The Schematic Ultra- miniature Transmitter

The coil is an ordinary MW spare's antenna coil on a small ferrite slab.The condenser mike is of the type used in tape recorders.A button trimmer is used for tuning .There's hardly anything more to be explained about the circuit.The assembly in a matchbox sized enclosure is suggested in Figure.The circuit should be made on a dot matrix board.The cell can be any kind of button(watch cell).


Adjust  the receiver to a dead spot. When no station is being received,begin speaking into the mike while adjusting the trimmer to obtain the loudest and clearest output at some point.Tape the trimmer there and the world's smallest(hopefully it all depends on how you make if)transmitter is ready to transmit.

Aplications are unlimited: bug,eavesdropping equipment,intercom,phone extenders,music broadcaters wireless microphone etc

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