This circuit was found in an ancient American documentation. The power supply is not given, but we have the voltages used. The relay is sensitive type for high voltage.
We find this vibrato configuration with transistors in a 1987 documentation. The components are still...
This circuit was obtained in a 1967 Electronics World. The components are still common today, the...
We found this voltage regulator for 5 V with current up to 10 A in an old manual of integrated circuits....