TV audio video transmitter circuit design project

A very simple TV audio video transmitter circuit can be designed using this schematic diagram. This TV audio video transmitter circuit can be used to transmit video signals from VCR ( or some other device ) to a TV without using any cable. Video signals input at jack J1 are first terminated by resistor R6 and coupled through capacitor C1 to clam

ping-diode D1. Potentiometer R3 is used to set the gain of the video signal; its effect is similar to that of the contrast control on a TV set. RF-transformer T1 and its internal capacitor form the tank circuit of a Hartley oscillator that`s tuned to 4. 5 megahertz. Audio signals input at J2 are coupled to the base of Q3 via C2 and R4: the audio signal modulates the base signal of Q3 to form an audio subcarrier thats 4. 5-megahertz higher than the video-carrier frequency. Transistors Q1 and Q2 amplitude modulate the video and audio signals onto an RF-carrier signal. The operating frequency is set by coil L4, which is 3. 5 turns of 24- gauge enameled wire on a form containing a standard ferrite slug. The RF output from the oscillator (L4, C7 and C9 ) section is amplified by Q5 and Q6, whose supply voltage comes from the modulator. Antenna matching and low-pass filtering is performed by C12, C13, and L1. To align this audio video transmitter you need to tune a TV receiver to an unused channel between 2 and 6. The TV must have an indoor antenna connected directly to it; an outdoor antenna or cable won`t work. Make sure both potentiometers (R3, R7) are in middle position and apply power to the transmitter. Adjust L4 with a nonmetallic tool until the TV screen goes blank, then fine-adjust L4 for the "most-blank" picture. After that you should see a picture on the TV screen: if you do, readjust L4 for the best picture; if you...

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