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.
This circuit was obtained from a 1977 documentation. The circuit does not require a symmetrical power...
This circuit is from an article in Radio Electronics magazine from August 1972. The circuit is...
The figure shows how to implement a filter against interference caused by the switching of a...