Speech processor - clipping and dynamic compression
To obtain the best modulation result of a transmitter you can use 2 ways: clipping and dynamic compression. Both methods have disadvantages: clipping - there is no constant signal carrier and so the transmitter has a tendency to be overmodulated or undermodulated and in dynamic compression degradation also happens because of the uncontrolled signal bursts due the time constant of the compressor’s regulator.
If you want to avoid these problems you can use this
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FET audio mixer
FETs are originally designed for high frequency applications but they can be used for audio frequencies and in fact they perform excellently in this area. This FET audio mixer is an example of FET’s versatility.
This mixer needs only four FETs and performs very well (actually you cannot expect a high quality mixer).
The mixer’s input impedance is determined by the resistance of the input potentiometers used, since the impedance of the FETs is very high.
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Basic infrared transmitter
This infrared tranmitter is intended for use with this infrared receiver.
It works with 2 - 1.5V batteries or a 3V lithium battery. To give a compact assembly and still a good frequency stability, the circuit uses a oscillator with outpashing network. Current consumption depends on power supply and duration as S1 remains pressed. When Ub = 2V,
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