This simple step of low power audio is from a 1975 documentation. The transistor can be a BC548, and the transformer of the type found in small transistor radios and recorders of the time.
The circuit shown in figure 1 is suggested by Maxim (www.maxim-ic.com) and makes use of the...
This high impedance circuit uses a 12 V lamp to test voltages in a car. We found it in a Popular...
This circuit was found in an Electronic Design. It makes use of a relaxation oscillator to trigger...