[Ynze] has built an audio amplifier that looks and sounds ... to drop his local 230V mains down to +25V and -25V. The amplifier circuit itself is simple – a few discrete components surround ...

We’re talking of course about the carbon microphone amplifier, a piece of telephone ... Being a resistor it can be placed in a potential divider circuit that produces some significant voltage ...

This can be accomplished with RF parallel amplifiers (Fig. 3.104). Figure 3.104: A parallel amplifier circuit without bias components. With parallel amplifiers, each transistor is on or off at the ...