video sync box - with colour bar

video syncbox elektor february 1984 The syncbox is a circuit for use with a video-audio modulator (VAM) or a video combiner. It provides all kinds of signals that are needed to build up a complete video signal. A syncbox can be used, for example, to fill up the space between two recordings on a video tape. The "noise" that would then normally appear can thus be replaced by a black image or a colour bar. video syncbox with colour bar This syncbox is an independent video signal source using an oscillator signal of 125 kHz to produce a number of basic signals that can be used for all kinds of video equipment and circuits. An external crystal-controlled signal can be used to clock the circuit if very high stability is demanded. Using the signals from the syncbox a black image (for video recorders) or even good quality colour bar can be produced. The circuit In the circuit diagram shown in figure 1 all signals are formed from the output signals of the 4040 (IC1). This IC, together with...