Oscillator type metal detector with switch controlled fixed biasing
US4323847A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 11, 1979 |
| Grant date | Apr 6, 1982 |
| Priority date | — |
| Expiry date | Jun 11, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/15
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus is described for detecting the presence of metal objects which may be subterranean. The apparatus comprises an amplifier equipped with a feedback network for forcing the amplifier into oscillation. The amplifier is critically biased such that the minimum gain necessary to maintain oscillation at the frequency of resonance is achieved. The presence of metal near the search coil which forms the tuned circuit of the amplifier loads the output circuit of the amplifier to a degree which suppresses oscillation. An indicator is provided to indicate when the oscillation has decreased in amplitude, whereby a metal object may be located.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.