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Thread: metal detector

  1. #1
    Senior Member T-1000
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    Default metal detector

    hi,
    i am making a real time mine detector robo....
    i need a very reliable circuit for detecting metals..
    something which should respond with gud range and be reliable too......
    plz don suggest any ckt using cs209a,tda etc. as they r not available in india.
    if u thought u r the only mad person on the planet.......u got serious competition here

  2. #2

    Default

    hi u can use a pulse induction metal detector principle (its explained on protovale 's website just google for the firm website address i dont remember it)
    essentially u need to have a pulse generator ( a 555 timer or any microcontroller with lookup tables/an internal sine wave generator can be used) these pulses are sent through an LC oscillator when a metal object comes in the oscillating magnetic field eddy currents generated increase the impedance and hence current level drops ....now u convert this current to a voltage (done by a simple resistor or even an op amp based circuit can be used) fed this voltage to a comparator when the reference voltage is suitably selected by u ( ths is hit and trial) then u can get an HIGH/LOW output that u can feed to a microcontroller ......
    in case u have deep pockets buy TCA BG505 IC(from infineon/siemens) from rsindia.com they take 3 weeks for delivery & it costs 342 bucks....
    in case u want to to draw u a circuit dia just mail me & in case of any query mail me...

  3. #3
    Senior Member Cyborg
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    Default

    you can make a variable reactance oscillator

    make a AF-LC oscillator using a fixed cap & a inductive search coil for sensing.....when it comes close to a metal....its frequency of oscillation changes...which you can obviously hear..

    its the easiest concept....but have to do some math on the coils dimesions to fix the inductance

  4. #4
    Super Moderator T-1000 docel's Avatar
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    Default

    HI FOLKS!!
    !. FM TX ANT AS METAL DET. 20 BUCKS FM RECEIVER DRIVES DIGGER MOTOR.I wonder if anyone read that....
    Any oscillator will detune when close to 'Ground' objects. If you fool around with a Radio, you will see the effects of touching the antenna- the signal strength will decrease or increase.
    The simplest method is to make a fm transmitter, say 100mHz. with a Loop antenna. A telescopic will also do. Off-tTune the fm receiver slightly. When the Tx antenna approaches metal or 'ground' it will be heard as a " strong' signal at the Rx. The speaker o/p can be routed to a Level det or window comparator for triggering some alarm etc,.

    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  5. #5
    Senior Member T-1000
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    Default

    thanks....
    ll give it a try
    if u thought u r the only mad person on the planet.......u got serious competition here

  6. #6
    Super Moderator T-1000 docel's Avatar
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    Did you?
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  7. #7
    Senior Member Cyborg
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    Default

    i have a metal detector kit by gala electronics very prompt response and i am using it in my robot

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