Can I use 5.1v zenor diode for voltage regulator from the previus shema ??
That depends on the soundcard you use. Some of the new USB soundcards have a lower DC idle voltage (1.25v instead of 2.25v).
If your card has the lower output AND you are using the original schematic, use a 3.3v zener instead of the 5.1v. A value of
100K for the gain adjustment (R5) instead of 50k will give increased gain range, and it is a good idea to use external
potentiometers for X Y gain (instead of trim pots), so that you can easily adjust image size when you need to.
Dean