This circuit generates the busy tone of ordinary telephones. The transistors can be the BC548 and the components of the T filter and the multivibrator can be changed to obtain the exact tone.
This circuit was obtained from an old Electronic Design. The components are from the period but...
Toshibas IC Brushless Motor Drivers Toshiba offers through Mouser Electronics a broad range of...
The 1: 1 transformer on this circuit found in a 1967 Electronics World can be wrapped around a...