Cathode-ray-tube protractor or synchroscope

A simple resistor-capacitor circuit permitting a visual indication of phase difference between two voltages on a cathode-ray-tube screen is presented. The phase angle is related to the orientation of a straight-line image on the screen. As the angle is changed, the line image rotates through an angle equal to twice the change. An angle scale can be put on the screen with angles up to 360 degrees shown on each side of the screen so the phase angle can be read opposite either end of the line image.