The presented circuit uses a PNP transistor, which can be the BC558. Observe the polarity of the supply. The circuit is suggested by Texas Instruments opto-electronic documentation.
This well-designed sinusoidal oscillator by Wien bridge was found in ancient European...
This is a circuit for testing small lamps and LEDs. The lamps that can be tested are the ones...
Found in a Popular Electronics from the 90's, this circuit can be implemented with almost any...