This circuit uses an impact sensor transistor called Pitran rare today. The circuit is from 1969 American documentation.
This oscillator uses a general-purpose transistor that can have BC548, BF494 or 2N2222 equivalents and...
This unusual circuit from a Popular Electronics of the 90s uses LED indicators, operating as a...
This circuit can be used to excite push-pull steps of audio amplifiers. From an audio signal at...