metaldetektor magnum free download

File name magnum.pdf

MAGNUM METAL LOCATOR PE ANDY FLIND Cheap metal detectors are usually disappointing in use whilst good ones tend to be very expensive. Although there is a lot of work involved in building the machine in this article, it can be completed for around Ј40-50, less than a quarter of the cost of most ready-made ones of similar performance. It is not strictly a design for the beginner to attempt, but a step by step construction and test procedure has been devised to make it as simple as possible. The only absolutely essential item of test equipment required is a reasonable quality test meter. Until now, most metal detector designs for the home constructor have been BFOs. True, there have been one or two notable exceptions, but even these were relatively unsophisticated examples of their type, so readers might be interested in a brief description of the basic methods of detection and the reasons for the choice of system used in this design. TYPES OF DETECTOR Broadly speaking there are five main ways of detecting metal; BFO (beat frequency oscillator), induction balance, pulse induction, off resonance, and the magnetometer. The latter works by detecting small anomalies in the Earth's magnetic field strength. It's fascinating but quite useless for treasure hunting since it can detect only ferrous objects. The BFO and off resonance types both operate by detecting the small changes in the search coil inductance which occur when a metal object is present. Both suffer from a basically poor sensitivity. Some sophisticated attempts have recently been made to produce a really good off resonance machine, so far without obvious success. Pulse induction detectors are another matter however; good ones are very sensitive indeed and some of the most expensive detectors currently available are these. They operate by exposing the ground to powerful pulses of magnetism and listening between the pulses for signals due to eddy currents set up in any metal objects present in the field. Despite their sensitivity they have a couple of important drawbacks. Their battery consumption is heavy due to the power required by the pulsed transmitter, and they are extremely sensitive to even tiny ferrous objects. Their use is thus primarily restricted to beach searching, where objects are likely to be buried at considerable depths, and where large holes can be easily and rapidly dug. On inland sites, their users can become discouraged by the frequent digging of large holes in hard ground to recover rusty nails, etc. This leaves the induction balance types which have become more or less the standard general purpose detector for both serious treasure hunters and detecting hobbyists alike. It has two coils in its search head, one of which is fed with a signal which sets up an alternating field around it. The other coil is placed so that normally the field around it balances and it has no electrical output. A metal object approaching the coils will distort the field, resulting in an imbalan