This oscillator for frequencies up to a few tens of kilohertz was found in a 1970s documentation. The transistor can be of general use. For the component values used, the frequency is 250 Hz.
This simple alarm circuit was found in a 1998 documentation. When the sensors are activated, the...
This circuit was found in an old American documentation. The integrated circuit used is uncommon...
Found in a 90s Electronic Design, this suggestion to have a higher voltage in a fixed regulator...