Metal detector circuit with mode selection and automatic tuning
US4303879A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 29, 1979 |
| Grant date | Dec 1, 1981 |
| Priority date | — |
| Expiry date | Jan 29, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/105
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A metal detector (10) is disclosed which has a transmit coil (48) and a receive coil (150) for detecting a metal object due to a change in the magnetic coupling between the coils (48, 150). The metal detector (10) has a plurality of operating modes and for each mode an operating parameter is selected and stored. Each operating parameter is used to generate a demodulation signal. A multiposition switch (36) is manipulated by an operator to select one of the operating modes. A logic circuit (191) is provided to route the demodulation signals to a demodulation circuit (110) to operate on a receive signal from the receive coil (150). An audible signal produced by the metal detector (10) is inhibited when operating modes are changed. An automatic tuning circuit (228) has selectable slewing rates for nulling the output from the metal detector (10).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.