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.
Adafruit Raspberry Pi Perma Proto PCB Kits Adafruit kits are available from Mouser Electronics...
The circuit shown is from the Motorola Linear Databook of 1990. This circuit converts signals in...
We found this circuit in a 2005 Linear Technology application manual. The circuit makes use of a...