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This might be plainly obvious but some experimenters may not know how to test their SD or GP detectors inside the house while carrying out modifications to the electronics. The SD and GP series do not have a tuned or filtered front end so that the detectors pick up every electrical glitch. The electrical interference that is inside a house can easilly overload the detector making it impossible to carry out experiments and compare the results.
I wound very small diameter coils of 4 inches to try to reduce the interference and it was somewhat effective. To get rid of all the interference one has to use a figure 8 type coil. For a Minelab machine you wind a standard coil so that it is .5 ohm and around 380 uH inductance, when you twist the coil into a figure 8 shape the inductance will reduce to around 300uH. Minelab detectors do not like operating when far removed from these coil specifications. It also is a good idea to use a Faraday shield on the coil to reduce stray capacitive effects. I use fine metalic mesh for my shields.
The material is available from http://lessemf.com best material is the stainless mesh or the Silver fabric, both work fine.
To test the detector I hang a suitable target from the ceiling over the coil, I adjust the target height and swing the target so I can just detect it as it swings over the coil. I then do various experiments and can judge the outcome.
I wound very small diameter coils of 4 inches to try to reduce the interference and it was somewhat effective. To get rid of all the interference one has to use a figure 8 type coil. For a Minelab machine you wind a standard coil so that it is .5 ohm and around 380 uH inductance, when you twist the coil into a figure 8 shape the inductance will reduce to around 300uH. Minelab detectors do not like operating when far removed from these coil specifications. It also is a good idea to use a Faraday shield on the coil to reduce stray capacitive effects. I use fine metalic mesh for my shields.
The material is available from http://lessemf.com best material is the stainless mesh or the Silver fabric, both work fine.
To test the detector I hang a suitable target from the ceiling over the coil, I adjust the target height and swing the target so I can just detect it as it swings over the coil. I then do various experiments and can judge the outcome.
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