This excellent 3-transistors audio preamplifier is suitable for use with low impedance microphones, small speakers and headphones as microphones or telephone pickups. The transistors may be the BC548 and power comes from a 9 V battery. Consumption is very low. The circuit was adapted from an English publication of 1979. The input and output cables must be shielded. The basic difference of this circuit from the previous version is in the input stage. The output stages are equal. If the circuit is powered by power supply, it must have excellent filtration. The level of the output signal is sufficient to excite most amplifiers.
