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WARNING SYSTEM

  • US 3,771,154 A
  • Filed: 12/27/1971
  • Issued: 11/06/1973
  • Est. Priority Date: 12/30/1970
  • Status: Expired due to Term
First Claim
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1. A warning system for emitting a warning signal upon change in position of an actuating member, comprising a sensing circuit in which a magnetic switch means and a capacitor means is included, said magnetic switch means being operable in response to a change in position of said actuating member to activate said sensing circuit, said capacitor means being charged during initial activation of said sensing circuit, a thyristor means triggered by said sensing curcuit to provide a signal after a predetermined period measured from the time said sensing circuit is activated by said change in position of said actuating member to the time said capacitor means becomes charged, said sensing circuit further including a first transistor with base-emitter circuit connected in parallel with said capacitor means, a second transistor with a base connected to the collector of said first transistor and a third transistor with collector connected to the gate of said thyristor means, the emitter of said third transistor being connected to the anode of said thyristor means, a flip-flop circuit responsive to the signal produced by said thyristor means and operable to provide an alarm signal, and alarm means receiving said alarm signal, said thyristor means being operable to sustain its signal and provide actuation of said alarm means even though said actuating member has returned to its initial position.

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