| 摘要 |
A level indicating circuit includes a pair of transistors, arranged as a differential amplifier and to whose bases an input signal is applied, a level-detecting circuit to supply to a meter or the like an indicating current whose level is related to the magnitude of the input signal; and a network connecting the collector of at least one of the transistors of the differential amplifier to the level-detecting circuit and establishing a threshold for the input signal such that the level-detecting circuit supplies its indicating current only when the input signal exceeds the threshold. The level-detecting circuit can include a transistor which is biased so as to begin conducting only when the magnitude of the input signal exceeds the dynamic range of the differential amplifier and drives one or the other of the transistors thereto to cutoff or saturation. |
