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Supply voltage monitoring device for automotive battery

  • US 4,217,536 A
  • Filed: 04/24/1978
  • Issued: 08/12/1980
  • Est. Priority Date: 09/14/1977
  • Status: Expired due to Term
First Claim
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1. A supply voltage monitoring device for automotive battery for monitoring the supply voltage of an automotive battery used as a power source for various on-board equipment, having an average voltage generation circuit for producing the average voltage of the battery supply voltage, a Zener diode which conducts only when the output voltage of the average voltage generation circuit exceeds the prescribed value, a first transistor connected between the Zener diode and the average voltage generation circuit, a second transistor controlled by the conducting Zener diode, a capacitor controlled by the output of the second transistor, third transistors controlled by the output voltage of the capacitor, and a light emitting diode whose light emitting state is controlled by at least the third transistors, and characterized in that the device is constructed so as to monitor the battery supply voltage by the light emitting state of the light emitting diode.

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