Found in a 1990s Popular Electronics, this circuit uses two transistors to boost the power of a 741 with audio signals. The power depends on the transistors used, which can be general-purpose types.
We can use the circuit shown below, obtained from a 1992 documentation. To turn a low impedance phone...
High-brightness LEDs of various colors and even white can be obtained easily in specialized...
This circuit is from an American publication about old neon lamps. The circuit is leak proof and...