This circuit generates short pulses. The transistor can be a 2N2222 or BC548 and the frequency is given by the resistors and the capacitor that can be changed.
This circuit is from 1990 documentation. It can be implemented with BC548 transistors instead of...
This circuit can be used to excite push-pull steps of audio amplifiers. From an audio signal at...
This charger for currents up to 100 mA was found in a 1980 publication. The transistor could be...