How to use a voltage meter pen to test the quality and polarity of high-voltage silicon stacks
The pen string is only a diode, and the positive pole is connected to the mains phase line. Hold either end of the silicon stack and touch the metal clip of the stylus. If the neon tube inside the pen is bright, hold the negative end of the silicon stack in your hand.
The neon tube inside the pen does not shine, and the silicon stack is held at the positive extreme. Swap the silicon stack end by hand, and observe the positive and negative measurements carefully. Both neon tubes were lit, and the high-voltage silicon stack was short-circuited.
The neon tube did not light up twice, and the high-voltage silicon stack was open.
