This detector work stable with various coil diameter - from 10 cm to 1x1 m 

Only 3 potentiometers

Low reaction for stones, what consists iron and ferrous oxides

You can use it for:

  - Deep searching (with big coil or frame)

  - General purpose metal detector

  - Searching on the beach

  - Searching meteorites

  - Searching gold (nugget)

Characteristics:

• Model on New Hobby: NH-173
• Mode: non-motion
• Manual and Auto Threshold
• Search coil: RED (you can buy it from the site). Also you can do it yourself (description in manual).
• Sensitivity: 25 cm for small coin, 30 cm for big coin.
• Indication: sound (speaker not included)
• Low battery indication
• Power: 12V
• Reverse power protection
• Consumption: ~140 mА
• Dimensions of PCB: 127 x 92 mm