This circuit can use a pendulum sensor. We found this configuration in a 1994 publication. The components used are common and the timing is given by the capacitor C1 which can be changed.
This electronic level or plumb indicator has two mercury switches as sensors. The indication is...
The circuit shown causes two LEDs to alternately flash at a frequency given by the capacitor. The...
This new Texas Instruments component consists of an inductive proximity detector that can be used...