AC THRESHOLD AMPLIFIER FOR USE IN FAILSAFE APPLICATIONS

摘要

An AC amplifier having a built-in threshold has a circuit structure inherently providing a single predetermined output mode under any conditions of failure of its individual components or combinations thereof. The circuit employs the impedance transformation characteristics of unity gain amplifier stages coupled by step-up transformers to preamplify the signal. Another step-up transformer coupled the last gain stage to a transistor threshold circuit employing the forward conduction voltage of its base-emitter junction for the threshold action. The circuit is so arranged that its output mode under failure of components or combinations of components is the "absence of dynamic output.