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.
Found in a 1990s American technical brochure, this circuit is intended for alarms that use as...
We found this circuit in an 80's Radio Shack publication. The circuit uses a company buzzer, but...
This oscillator can generate 2 to 10 MHz signals and was found in an American 1980s documentation. The...