Deep seeking metal detector project Deltapulse

Info from CoPilot:

”Delta Pulse
Type: Pulse Induction (PI)

Popularity: One of the most widely discussed and modified detectors on Geotech1.

Performance:

Known for good depth detection, especially with large coils.

Can detect large metal objects (e.g., a shovel) at up to 2 meters in air with a 1x1 meter coil.

Customization:

Highly modifiable; users often tweak components like R40 resistor values and shielding for better stability.

Sensitive to coil design—poor coil construction can cause overheating or signal loss.

Use Case: Favored by hobbyists and tinkerers who want to build or modify their own detector.”

Selling 2 nearly finished Deltapulse units (PCB version 5.0) including enclosures.
Success in getting these to work satisfactorily was not achieved. This may be due to insufficient electronics knowledge or interference from a 220 kV power line located 150 meters from the house. Interference was measured on the supply voltage, which could explain the functional issues. Those living near a power line should likely avoid attempting this project.

NOTE! This is not a beginner’s kit, as metal detectors transmit and receive electromagnetic pulses and can be disturbed by power lines. An oscilloscope is required to tune and troubleshoot the detector.

More information about the Deltapulse, including an active forum thread for troubleshooting help, can be found here: www.geotech1.com. The Deltapulse was designed by the user "kt315" on the Geotech forum, who also sells the PCBs for 14 Euro each.

Included items:

• 2 assembled Deltapulse PCBs mounted in aluminum enclosures. All ICs are mounted on high-quality IC sockets.
• Plastic potentiometers mounted on the front panel to regulate Depth, Discrimination, GEB (Ground Exclusion Balance), Sensitivity, and Threshold.
• Combined green/red LED on the front panel to indicate power on and low battery voltage.
• Reset button on the front panel.
• Rear panel connections: Power supply (12V external battery), on/off switch, fuse, and coil connector.
• Built-in speaker at the bottom of the enclosure.

Specific details:

• Unit #1 has a pre-drilled hole for a connector (included) used by Lorenz to connect their coils. This can be used to test the unit with a Lorenz coil, though there are no guarantees regarding compatibility.
• Test coils: One 395 uH (approx. 10 cm diameter) and one 431 uH (approx. 30 cm diameter).
• Cables: 3 short, different shielded cables. The designer states that 1x1m coils must not be used indoors, as excessive interference may damage the detector. Testing should be done with small coils indoors.
• 2 connectors for external coils (Lorenz compatible).
• 2 DVDs with extensive metal detector information from user "kt315" on the GeoTech forum.
• Battery holders: One for 6 AA batteries and one for 10 AA batteries (provides approx. 12V with rechargeables).
• 2 panel meters (0-50 uA): Optional; audio from the speaker is sufficient to indicate metal.
• Documentation:
  
  • Circuit diagram (A3 print on photo paper).
  • Bill of Materials (BOM).
  • Full-color print of an assembled PCB.
  • Simple step-by-step component assembly guide.
  • Component layout diagram (2:1 scale).
  • Technical papers describing oscilloscope waveforms for test points T2 through T5.

Terms of sale:
Sold as-is/defective, as they are currently non-functional. No returns.
A bargain for a skilled hobbyist, as deep-seeking detectors are very expensive (a Lorenz Z2 costs approximately 50,000 SEK).
Questions are welcome. Smoke-free and pet-free home. Combined shipping available.