This high quality circuit with complementary symmetry was found in an Electronics World of 1966. It can be made with modern transistors like the BD or TIP series.
This circuit can generate signals from 80 to 800 Hz with an amplitude of 0.3 V. We find it in a...
We found this circuit in a Hands-On Electroncs from the 90s. The circuit uses an LED indicator. Diodes...
We found this configuration in a documentation for radio amateurs from 1974. The circuit can be...