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Point N--Diode Load Resistor

Back    Signal should be heard.

   By the magic of demodulation the signal is now at audio frequency.

   The high-frequency wave has done its work of carryzng the message and has been dismissed. Only the original modulating frequency (voice or music) should remain.

   A detailed discussion of demodulation is beyond the scope of this paper but may be found in any good textbook. Successful signal tracing is first of all a matter of the understanding. The hand that moves the probe must be guided by an intelligence that knows the function of each part and its relation to every other part.

   The demodulator or detector Is simply a rectifying device that passes the postive half of the high-frequency wave but gives poor conduction on the negative half. By means of filters, these positive pulses are joined to form the original modulating wave.

   For purposes of signal tracing, adequate knowledge of the detector circuit can be obtained from a study of the functional diagram given in Fig. 7.


Fig. 7. Functional diagram of a typical detector circuit.
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