This circuit allows the activation of a remote telephone bell made with a common piezoelectric capsule. The circuit does not need power, as it is powered by the line call signal itself.
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...