METAL DETECTOR THUNDER 3
THUNDER-3 SCHEME AND DESCRIPTION
The metal detector is designed for searching for metals in the ground (and beyond) with discrimination by types (ferrous and non-ferrous). Type: VLF-IB. The search for metal objects is carried out by scanning the magnetic field of the ground and registering changes in the primary field due to the influence of metal, followed by phase discrimination and notification by a sound signal. With certain skills, it is also possible to determine the relative depth (size) of the object. What sets the device apart from analogs is an effective system for suppressing the influence of the ground, “hot” rocks, and sensitivity with a small sensor diameter, allowing for the detection of small and very small objects. The device incorporates original author solutions and a modern component base. The swinging motion is powered by powerful CMOS transistors. The channel amplifiers are built on precision, low-noise operational amplifiers.
Thunder-3, or Гроза 3, is an analog metal detector developed in 2004-2005 that operates on the VLF-IB principle. The metal detector features a two-tone sound mode (for ferrous and non-ferrous metals) for target recognition and the ability to disable ferrous metal detection. In addition, the version of the metal detector that came to me for repair has been equipped with a LED scale indication called “Молния” (Lightning).
Scheme of the Thunder-3 Metal Detector
Photos of the circuit board of the metal detector ‘Гроза 3’
Photos of the indicator scale board ‘Lightning’ for the metal detector ‘Гроза’
This is done to ensure that the circuit “pays attention” to the input signal and its changes as frequently as possible during one half-period, not just compensating for 0 at its output. That is, uniformly, several times during the half-period, and since the frequencies are not multiples, a “sliding phase” effect occurs. This has practically reduced detector errors (losses) to 0. Interference penetration from the use of different, non-multiple frequencies is absent. The difference and sum of their frequencies are too large for us to detect. What magnitude of imbalance can there be, mismatch of the coil?