With this simple circuit it is possible to simulate a telephone line for carrying out repairs on telephone sets. The transformer must be 36 V and the diode can also be 1N4004.
Suggested by Maxim in documentation from the 90s, this circuit has its response curve given next to...
Found in a 1969 Ferranti documentation, this circuit uses only bipolar transistors from that time....
Found in a 1960 General Electric documentation, this crowbar circuit blows the fuse in case of...