I am using Schmitt Trigger CD40106BE to make an PWM oscillator with controllable duty cycles. The schematic is shown below:
However, the LED that should be blinking is constantly on. After some trials and errors I found that even when nothing other than Vdd(9V battery) and Vss(ground) are connected to the CD40106, input pins of the chip with nothing connected shows a 5.4V potential difference relative to the ground (battery negative) and the output pins show a 9V (typical behavior).
Why do I have a 5.4V on my input pins with nothing connected?