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Battery power supply circuit which supplies correct power polarity irrespective of battery orientation

  • US 5,623,550 A
  • Filed: 03/08/1995
  • Issued: 04/22/1997
  • Est. Priority Date: 03/08/1995
  • Status: Expired due to Term
First Claim
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1. A hearing aid comprising:

  • a microphone for transducing audio waves into electronic signals;

    an amplifier for amplifying the electronic signals;

    a receiver for transducing the amplified electronic signals to sound waves;

    a battery for supplying power to the amplifier; and

    battery switch means including first and second battery terminals in electrical contact with the battery for supplying power of correct polarity to the amplifier irrespective of battery polarity orientation, the battery switch means comprisinga first transistor switching circuit connected between the first and second battery terminals and responsive to voltage from the battery to through-connect a negative polarity power signal therethrough, the first transistor switching circuit comprisinga first n-channel MOSFET having gate terminal, a drain terminal, and a source terminal, the drain terminal being connected to the first battery terminal the gate terminal being connected to the second battery terminal,a second n-channel MOSFET having a gate terminal, a drain terminal, and a source terminal, the drain terminal being connected to the second battery terminal, the gate terminal being connected to the first batten/terminal, the source terminal of the first n-channel MOSFET being connected to the source terminal of the second n-channel MOSFET and supplying the negative polarity power signal, anda voltage divider circuit disposed between the first and second battery terminals and connected to the source terminals of the first and second n-channel MOSFETs, the voltage divider circuit comprisinga first resistor having a first terminal connected to the first battery terminal, and a second terminal, anda second resistor having a first terminal connected to the second battery terminal, and a second terminal connected to the second terminal of the first resistor, the second terminals of the first and second resistors being connected to the source terminals of the first and second n-channel MOSFETs, anda second transistor switching circuit connected between the first and second battery terminals and responsive to voltage from the battery to through-connect a positive polarity power signal therethrough.

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