What is the output of AND gate if sine wave is input?

Answer 1

I assume the sine wave input is pure AC, meaning this signal is positive, and negative, as would come from a transformer winding. To not damage the fragile input to the AND gate, you should have a limit resister, say 1K ohm to 10 K ohm. Then the output of the AND gate will be a very clean square wave. It will be in phase with the input sine wave. You can add a small capacitor from the AND gate input to tr ground.

IMPROVEMENT: The best kind of gate to use for this circuit is called a "Schmitt Trigger", which will really clean up the signal. It is only available as inverting, 1, 4, or 6 per package. You can easily use an inverting NAND, and run it through 2 gates to get your phase back to what you want. So for what you are doing, use a 10K input, to a 100 pF cap to ground, going into one section of a 74HC14 (6 inverters in one package), and then go through another section, if you need to get back to 0 degree phase shift. With the 2 inverters in a row, you can have 2 phases available. Or, you can add another R-C delay between the 2 sections, and make the phase shift to whatever you need. 90 degrees, no problem. With 6 inverters, you can phase shift on and on, and make all kinds of poly phase outputs.

MORE FUN: With the Schmitt gate, you only need an R and a C from the output back to the input, and you will make a very stable Square wave generator. With a single diode, you can make a "one-shot" circuit, for constant pulse width. You can even make a PWM circuit, by DC biasing the input.