This circuit was found in a Ferranti documentation from 1969. The transistors are common types of the company at the time. Smaller equivalents may be used. The output power is of the order of 150 mW.
Suitable for recovering tape recorded media from a common tape player mechanism, this circuit is...
This circuit is indicated to operation with piezoeletric transdicers or other with high impedance...
Of course, the current is extremely small, but a voltage of 300 V can be obtained from 9 V of a...