This harmonic oscillator controlled by crystal was found in an American documentation of the 90's. The circuit uses transistors of the time. Current equivalents can be used.
To obtain triangular signals, we have the circuit in the figure that uses two amplifiers. One of...
This circuit was found in an old Electronic Design. It makes use of sidacs and operational not very...
This circuit was found in an American publication from 1969. Transistors are from the time and can be...