SIMPLE_VIDEO_RECEIVER

Published:2009/7/14 21:28:00 Author:May | From:SeekIC

The IF input from the tuner is fed into an MC1350 amplifier (IC1) through capacitor C4. The 56Ω input resistor R8 approximates the impedance of the tuner's 50-Ω output. The IF amplifier is tuned by variable inductor L1 and capacitor C1, and its gain is controlled by potentiometer R5. The output of the IF amplifier is coupled into an MCl330 low-level video detector (IC2) through C5. The optional LC trap circuit, consisting of C8 and L3, can be adjusted to eliminate a specific signal, but the circuit will work well without the trap. The MC1330 is also tuned with a tank circuit, consisting of L2 and C9. The video outputs are biased with resistor networks. The noninverted video is fed into the base of a 2N3904 NPN transistor Q1 configured as a unity-gain, common-collector, buffer amplifier for impedance matching. The primary video output is taken from the top of Q1's emitter resistor R6, and the auxiliary video output is taken from pin 5 of IC2. The VSB output is an ac-coupled version of the primary output, and it can be used for any sound output you wish to use in the future, The switching carrier output can be used for automatic fine-tuning (AFT) circuits.



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