Modern variations may use explicit level detectors and gain-controlled amplifiers.
2.
Because of the wide slew-range and lack of positive feedback, the response of all the open-loop level detectors described above will be relatively slow.
3.
For example, an overcurrent protective relay may have a AC to DC power supply for the input circuit, a level detector circuit and an RC time delay circuit.
4.
Against the marine transmitter, the receiver combined a square-law : Power-level detector with cross-collation of a local copy of the pulse against the received signal.
5.
A " voltage level detector " can be obtained if a reference voltage " V " ref is applied to one of the op-amp's inputs.
6.
A " zero voltage level detector " ( " E " i = 0 ) can convert, for example, the output of a sine-wave from a function generator into a variable-frequency square wave.
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