Transformerless line powdered digital AC voltmeter

Claim 1

A transformerless line powered digital AC voltmeter for measuring AC voltage on an electrical line obviating the need for a separate internal electrical battery or external source of electrical power for the voltmeter operative electrical power comprising: means operably connected to the electrical line to receive the AC voltage to be measured, said means converting the AC voltage to digital electrical signals for a digital output indicative of the AC voltage input, said AC voltage converting means including a half wave rectifier and voltage divider circuit to convert the AC voltage to half wave DC voltage and reduce its magnitude, DC voltage modification means operably receiving the reduced half wave DC voltage, and an A/D converter connected to said DC voltage modification means; means operatively connected to said A/D converter to receive said digital electrical signals and visually display them in a readable form; and means operably connected to the electrical line being measured and to said AC voltage converter means providing a source of operative DC electrical power to said AC voltage converter means, said means including an AC/DC converter and circuit means to assure that a minimum AC electrical voltage input to said AC/DC converter is provided, said circuit means assuring minimum AC voltage input defining a series resistor-capacitor circuit interposed the electrical line measured and said AC/DC converter.