This circuit was found in a Popular Electronics from the 90s. The transistors are general purpose, and the gain depends on the ratio between R2 and R1.
This circuit for several frequencies was obtained in an American documentation from the 90s. The...
The 2 uF capacitor used in this circuit must be of excellent quality with a minimum of leakage to...
When the 24 V battery voltage drops below 18 V, this circuit cuts off its discharge. The circuit...