Compact metal detector of the balanced induction type
US4423377A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1980 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Nov 12, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/107
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A metal detector is disclosed which has a transmit coil, a receive coil, and circuit means for detecting metal object due to a change in the magnetic coupling between the coils. Circuit board arrangement techniques are disclosed which enable the close placement of the transmit and receive coils and the circuit board, thereby allowing packaging of the metal detector in a small package. A low battery voltage indicator circuit is provided to warble an audio indicator signal to indicate sufficient battery voltage. In the event the battery voltage drops below a certain level, the warbling of the indicator signal ceases and a steady tone is generated thereby indicating a low battery voltage condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.