SCREWDRIVER AS A LONG-RANGE INDICATOR OF AC VOLTAGE

摘要

Proposal belongs to the domain of electronics, namely to electrical network voltage alarm-indicators, structurally assembled in a screwdriver's grip. It may be used for alarm on "presence" or "non-presence" of alternating 50 Hz frequency electric voltage in a network, for detection and location of under plaster hidden phase leads. For this purpose there is necessary to have a secure alarm operating without direct ohm contact to being measured leads. For the stated reason electrical network voltage alarm, comprised of screwdriver metal part of, a stick which is fixed in the grip and made of electricity non-conductive material, inside the grip there is closed space for installation of electric circuit, that consists of resistor and indication ray. In addition between the screwdriver's metal stick and the first electrode of resistor there are switched on connected in parallel voltage follower, amplifier with logarithmic transfer coefficient and detector, a semiconductor diode, of which the common contact with resistor connected to the input of sound voltage converter and to the first electrode of filtration capacitor. The output of converter connected to piezo-converter serving as alarm. The second electrodes of resistor and filtration capacitor are connected to alarm's internal earth, to negative pole of power-supply source (galvanic element), the positive pole of which through a switch is connected to voltage follower, logarithmic amplifier and converter power-supply circuits. Voltage follower and logarithmic amplifier are made of two operational integrating amplifiers connected in parallel and converter is made of two voltage controlled generators connected in parallel, which consist of four logical AND-NO integrated circuits.