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 found in a 1980s telecommunications publication. The circuit uses a diode bridge to...
This circuit is from an English magazine from 1980, but it can be easily assembled with more...
The indicated circuit is an intermittent one in which we use two 555 integrated ones, one as a low...