This circuit was found in Mullard's transistor application manual from 1960. More modern transistors can be used. The zener diodes used have the indicated voltages.
This circuit, suggested by National Semiconductor, decodes audio signals from stereo TV...
Found in a 1970 documentation, this circuit makes use of 741 operational amplifiers that are...
Suggested by General Electric in 1967 documentation this circuit uses an isolation transformer to...