This low power circuit was obtained from an American 80's documentation. The circuit indicates the voltage of a battery being trimmed by the trigger point. The transistors can be the BC549.
MXT1665T-A Family from Microchip Brings the User Experience of Multi-Touch HMI into the VehicleCHANDLER,...
This circuit can use a pendulum sensor. We found this configuration in a 1994 publication. The...
This unusual configuration, due to the component it uses, was found in an old European...