This circuit operates at a voltage of 1.3 V from a single mercury cell. We found in an old documentation and for the components used the frequency is 500 kHz.
May 2016 - Mouser Electronics is sourcing the new high-performance audio amplifiers with bipolar...
These basic bass controls were obtained from an article in Electronics Now magazine in February 1995....
PIC16F19197 Microcontroller Family Combines Battery-Friendly LCD Drive with Core Independent...