| 摘要 |
<p>The detector circuit for testing proximity switches employing oscillating circuits, consists of a built-in battery supply (3) across which is connected a potential divider of two high-value resistors (10, 12) and one low-value resistor (11) in series between them. Across the centre resistor are connected the inputs of an integrated circuit operational amplifier (2). In series with the non-inverting input of the amplifier is a pick-up coil (1) or search coil, which is used to detect oscillations in the proximity unit under test. The test circuit is arranged to provide min. damping of the oscillatory circuit to which it is coupled. If oscillations are present, negative pulses appear at the amplifier's output (9) to drive a l.e.d. or similar indicator (4).</p> |
