This circuit, from an old American publication, can be modified for better performance with more modern components. For example, instead of the original T1 we can use a TIP41 and directly feed a low impedance speaker without the need for a transformer. Changes in R8 may be necessary to obtain a lower resting current. Resistors R2 and R3 determine the sound effect and can be changed over a wide range of values. For the original version, use a BC548 on the output and a small transformer obtained from an unused transistor radio.
