We found this simple protection with zener diode in a 1967 Motorola documentation. The zener diode is 18 V, but the components can be changed for operation with other voltages.
The operational amplifier can be of any type in this circuit, found in a 1974 publication. The...
Found in a 1967 General Electric SCR manual, this circuit triggers in case of excess current,...
With this configuration it is possible to obtain an 80 dB gain from two 741 operational...