This circuit was obtained in an American documentation from the 80's. The transistors can be equivalent to those indicated and the crystal can reach a few tens of megahertz.
This 1998 circuit controls the volume in a stereo system by touching switches. The circuit is for...
A 25 mVpp applied to the input of this circuit produces in the output a 1 Vpp signal. The...
The basic integrated circuits of this 1988 multimeter are no longer very common today, but if...