The operational amplifier used in this circuit is uncommon today, but the configuration can be made with more modern operators. The power supply is symmetrical.
Found in an English publication from the 1980s, this circuit can be built with equivalent...
This circuit from a Radio Electronics from October 1965 shows how to obtain the action of an SCR...
This variable high pass filter covers the range from 23 Hz to 700 Hz with the components used. The...