The modern development of the metal detector began in the 1930s, with the founding of Fisher Research Laboratory by Dr Gerhard Fisher in Palo Alto, USA.
However, it was one Lieutenant Josef Stanislaw Kosacki, a polish officer serving in the Signals Corps of the exile Polish Army stationed in St Andrews, Fife, Scotland early in World War II.
He refined the design into a practical detector, these “Polish Mine Detectors”€� were rushed to North Africa to help win El Alamein. Kosacki never patented the device or improved techniques and therefore made no money from his work. However he did received the Polish Silver Cross, and King George wrote him a personal letter of thanks.

After the War, a great deal of equipment was sold off as surplus at a fraction of its production cost, including Army Mine detectors, thus the hobby began. As the affluence of fifties America turned its wartime skills to the burgeoning consumer electronic sector, new names entered the field. Whites Electronics of California and Charles Garrett, who pioneered the BFO (Beat Frequency Oscillator) machine. Advances came year on year with the development of transistor based machines.  Whilst the Americans made great finds in their limited historical fields and “ghost towns” the handful of these new lighter sensitive machines that made it to the UK had a boon time of finds back through Medieval, Viking, Saxon, Roman, Iron and Bronze Age coins and relics and even Neolithic gold.

Technical advancement in detectors barely slowed, the next big “must have” was the development of the induction-balance system, where two coils are set up in a “null”. Any metal in the vicinity of the coils caused them to no longer “null” circuits in the control box detected this imbalance triggering the production of a change of tone in the machine's speaker or headset. The next step in a better detector was circuitry that could sense or process the signal to determine the metal type being detected. Every metal produces a subtly different response, but many metals have almost identical responses, wouldn’t you know it the response to gold and silver is close to tinfoil or that other bane of detectorist’s the dreaded “ringpull” So whilst discrimination is possible it must be used with caution as the more trash metal that is rejected the more likely that a valuable gold or silver find will be missed.

Pulse Induction(PI) detectors have been in existence at least as long as Induction Balance machines.  PI machines do not have a balanced circuit attempting to sense a change in that balance. Instead PI generate a very strong pulse (hence the name) of electromagnetic energy.  The circuit then effectively listens, expecting the pulse to die away over time (fractions of a second). However in the presence of metal the electromagnetic pulse “rings” and persists in the metal for the briefest of moments, this is detected and alerts the operator. The huge advantages of PI detectors is that they are virtually unaffected by ground conditions.  Most IB or BFO machines can be influenced by minerals in the ground, causing “falsing”€� i.e. bogus signals.  This makes PI’s very popular with beach detection and gold prospecting. So why aren’t we all using PI’s? Well they simply love iron, even the smallest scrap will give strong signals from great depth. ”Swings and roundabouts”.

The mainstream IB detectors have now been further developed in to Motion Machines.

The detecting community in the UK has moved along way from those early boon days with surplus mine detectors. Most detectorists would not consider themselves “Treasure Hunters”.
By developing a working relationship with like minded archaeologists and museum staff, we have become recorders of the nations past, changing the accepted view of the UK history in some cases and always expanding our personal knowledge of our local history. For more information on the modern detector community see the links page for sites such as PAS and the NCMD.