World's Simplest Audio Amplifier:

World’s Simplest Audio Ampifier –it GLOWS!: I came across this design by accident. The design is simple, but it is not very practical at all. I was able to construct a working version of this circuit and it did prove to work, after many hours of operation, the power transformer failed as I neglected to use a suitable one that could actually provide the current necessary.

The amplifier is a power amplifier to drive a speaker. Voltage and current both need to be amplified. I cheated for the voltage section. The entire pre-amp consists of one 741 op-amp per channel.

The current section consists of two transistors wired in a darlington arrangement. The front end is a typical 2N2222 while the second is a 3055. Both units are NPN type.

In the absence of many components, a light bulb, (yes!) is wired into the circuit. The light bulb is there to take in some current from the power supplies. When driving the unit to loud levels the light bulb will fluctuate a bit.

The amplifier is class –A type which may be desirable for some. The actual sound produced from such few components was quite good, except that the unit acts as a furnace heater, and night light at the same time.

The amp I built squeezed out about 5-10 watts. My friend Shawn liked how it sounded. It didn’t seem like five watts, they were “loud” watts.