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.
The output voltages of this power source are selected by a switch according to the capacitors. The...
This circuit is from a 90s Popular Electronics. The circuit employs a ZN461E that is not a common...
This circuit was found in Siliconix documentation from the 1980s. Equivalent operational...