I found tis circuit in na old documentation from 1958. The circuit uses germanium transistor availble that time and hard to obtain today. The circuit is indicated for phono applications using variable reluctance transducer.
January 6, 2016 - Mouser Electronics, Inc. is now stocking the TPS25810 USB Type-C™...
The tone produced by this circuit depends on the capacitor and the adjustment of the...
The figure shows how to use the LM3914 bargraph with expanded scale. The circuit has two...