| 摘要 |
<p>994,681. Fountains. MOBILCOLOR Inc. March 27, 1963 [April 13, 1962], No. 12139/63. Heading FIX. [Also in Divisions G4, H2 and H3] A system for controlling an electrical device in response to accoustic signals includes unidirectionally conducting means 94, 95 which conducts current only for a selected portion of an a.c. cycle, the duration of conductive portion being determined by the amplitude of the acoustic signal. As described audio input signals from a musical instrument or voice are fed via an input amplifier 14 to three filters (e.g. band pass filter 15) which divide the input signal into low, medium and high frequency components. The medium frequency output from filter 15 is fed via a detector stage 18 having a variable time constant controlled by switch 66 to a pulse generating circuit 19 comprising transistor 72 and unijunction transistor 80. The transistor 80 is supplied with unsmoothed rectifier a.c. between its bases 81, 84 and at a point in the a.c. cycle determined by the amplitude of the audio signal at the base of transistor 72. This becomes conductive to discharge capacitor 76 producing a pulse in transformer 78. The output pulses from the transformer 78 are used to trigger a pair of SCR's to supply power to the loads 99, 100. Load 99 is a coloured lamp, and load 100 is the control motor for a pump producing a water spray. Similar lights and pumps are controlled by the low and high frequency components by means of similar control circuits.</p> |
