i shared before 1- KROT2-XM Project (nor for beginners upper modarate have microchip firmware professional one ( have full firmware and working ) and 2-Easy build nice metal detector project russian Pirate metal detector ( need for moderate need some russian tecnology information ) .....
mybe that projects not worked for them...
But this one Nice , have simple construct and really usefull lvl beginner to modarate
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i think everybody will have construct own metal detector )
ok lets start for construct...
Metal detectors have two oscillators. One is tunable and the other is "Fix" with a loop. Both are "Tuned" at same frequency. Outputs from this two oscillators are then mixed in a mixer which produces only the difference. Means, if both oscillators are at the same frequency, there is nothing heard in the speaker.
To start with, you need to "Zero beat" both oscillators or say "Null" them while keeping your detector in the free air, away from metal objects. Use the tuning control provided for this purpose.
Once this is done, start placing detector around metal objects and you will notice that "Zero beating" is getting disturbed and an audio tone from the speaker is heard. Wow, the detector has found a metal & its working!!
The Circuit:
Both oscillators are built using MPF102 or J310 FETs. The Mixer is BF998 dual gate MOSFET.
Audio IC amplifier is LM386 which drives a speaker.
I have used a stabilized supply for two oscillators and mixer. U1, a 78L05 is doing this job nicely.
Circuit is being designed on a Single Sided Glass Epoxy Printed Circuit Board. It will be using PCB mounted volume control and a variable capacitor to tune the oscillator. (or varicaps & a pot) However, final design may change.
Not: i will not provide any files here but youll take more documents,Schematic and Possible Loop Design from author nina.
thats the web page from owner nina :
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http://www.foxdelta.net/detector.html
( new webpage from her )
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« Last Edit: March 18, 2015, 07:44:51 pm by cool2010 »
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