Obtained in an Electronic Design from 1968, this circuit has the voltages determined by the zener diodes. Transistors can be modern equivalents.
The circuit is from 1980s Linear Technology documentation. The components are of the time and...
This circuit was obtained in a 1977 magazine, but it can still be easily assembled, as the...
This circuit is from a 90s Popular Electronics. The integrated circuit is from that time. The...