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Small Metal Detector II

2014-11-06 05:07  
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A Simple design based on a CS209A IC that can give surprising results and draws very little current from a 9 volt battery. It worked good on the Bench, But not so good outside for general metal detecting. But Definately a good design for detecting studs in a wall, with the right coil! This particular circuit was built so it can be used with anLED and Buzzer or just the LED or just the Buzzer. Battery voltage can be up to 20 volts, but it doesn't addto the sensitivity. In Addition, Changes to the Potentiometer value can be made, adding a smaller pot in series to make a more sensitive trip point. visit page.Small Metal Detector II - schematic
This circuit operates on the principal of changes in `Q`of the coil. So it is important to try and make a High Qcoil! But I found that even simple coils gave fairly goodresults! It is recommended to use `Litz` Wire, But I justused vinal covered wire on one and also another with magnetwire and I got pretty good results with both coils.Having now put a board together and a few tests outside,it appears the coil needs a Faraday Shield.Unfortunately, Litz Wire is hard to find, but it does help!Additionally a coil wound on a `Power Ferrite Rod` can givegood sensitivity as well as abn Accurate Pin-pointing effectof metal objects!I obtained Free Samples of the chip from `On Semiconductor`,but unfortunately most of you will have to buy it.Etched and drilled PCB's are available for $3.00 ea. US Funds,Plus a Postage cost of $1.00.But this is NOT SUITABLE for the Surface Mount Package.I can No Longer Supply the CS209It is available from Some Sources, But only in the Surface Mount Package,And with a Minimum Order of 100 Pieces. visit page.