High performance video mixer - find the right combination!

7-86 — elektor july/august 1982 high performance video mixer ■■_ Terminals, (the interfaces between computers and video screens), have to output two synchronisation signals in addition to the actual video signal. The Elekterminal also contains a video mixer which combines the two signals into the single video display control signal. The H and V sync signal control the horizontal and the vertical deflections of the electron beam, respectively, while the video signal incorporates the picture infor- mation. All three signals are com- bined in the mixing stage around T1 and T2. 11111IIIIIII1111 and R3. Transistor T1 operates as an emitter follower. P1 sets the amplitude of the output signal, enabling the circuit to be adapted to any type of monitor and/or TV set. A monitor will have to be used, should your TV not have a video input socket. The video combiner is suitable for band- widths up to 25 MHz. V Sync T2 = BC 547B 82514 =tp BSX 20 find the right combination! T2 mixes the s...