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Video-signal generator with PIC16C84

TV lines interlacing It was necessary to view an output from my camera chip on a common TV. I have tested this circuit only with Merkur TV type, but I hope it'll do for others as well. Next timing pictures are taken from a textbook and that's the only documentation I had.

Time diagram of hf voltage from transmitter Synchro pulses between two frames

Next picture shows a part of circuit which makes video signal. The principle of that circuit is following - the output Vo2 is periodically connected to voltage levels Vout and Vimp that corresponds to a pulse voltage and to the black level voltage. All is driven by PIC16C84.
Vo1 signal is the amplified output signal from camera chip.
signal description range
Vout black colour level trimmed by R9 0 .. 5V
Vimp sync pulses level trimmed by R3 0 .. Vout
Vo1 amplified output signal from camera chip >= Vout
The polarity of output signal makes white voltage higher than black level voltage.

Generator schematic

It is possible to get all schematic (50k) of the test board. There is documentation (27k) in OrCAD for Window$ and source code (3k) for PIC16C84.

All the best and good luck from Petr Simandl
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Last change : 14.4.2000