David R. Vogelpohl

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Indianapolis, IN, US

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Patents Grantslast 30 patents

Information Patent Grant
Electronic tone ringer with distinctive signaling circuitry
- Patent number 4,567,333
- Issue date Jan 28, 1986
- AT&T Technologies
- David M. Embree
- H04 - ELECTRIC COMMUNICATION TECHNIQUE
Information Patent Grant
Method and circuitry for encoding telephone ringing signals
- Patent number 4,508,937
- Issue date Apr 2, 1985
- AT&T Information Systems Inc.
- William A. Burger
- H04 - ELECTRIC COMMUNICATION TECHNIQUE
Information Patent Grant
Electronic tone ringer
- Patent number 4,491,691
- Issue date Jan 1, 1985
- AT&T Bell Laboratories
- David M. Embree
- H04 - ELECTRIC COMMUNICATION TECHNIQUE
Information Patent Grant
Relaxation oscillator with plural constant current sources
- Patent number 4,292,604
- Issue date Sep 29, 1981
- Bell Telephone Laboratories, Incorporated
- Milton L. Embree
- H04 - ELECTRIC COMMUNICATION TECHNIQUE
Information Patent Grant
Electronic tone ringer
- Patent number 4,276,448
- Issue date Jun 30, 1981
- Bell Telephone Laboratories, Incorporated
- Milton L. Embree
- H04 - ELECTRIC COMMUNICATION TECHNIQUE