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Coil amplifier

Discussion in 'General Electronics Discussion' started by camerart, Oct 25, 2010.

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  1. camerart

    camerart

    85
    2
    Aug 18, 2010
    I made a coil amplifier a year or so ago, for locating a signal wire position. It gives 2X outputs, and connects to a PIC A/D inputs for the calculation. See attachment: coil Schematic.jpg

    It has caused problems from the start. It wasn't strong enough, so 2X transistors were added 'TR1 TR2' a second Diode was added, in series with D3, as a voltage lifter. The LM324 has a problem where if any pin receives -0.3V, the chip gets upset, so Schottkey Diodes were added at pins -IN, pointing towards GND.

    Sometimes the whole thing works fine, then something changes, and the calculations go out.

    When I used it at first before adding the Transistors, I'm sure the output range was 1to5V now it is app 0.5Vto1.2v So a weak signal on one side won't register and the other side could be reversing due to the -o.3 LM324 on pin problem.

    I hope this makes sense. Thanks.
     
    Last edited: Oct 26, 2010
  2. bureaupro

    bureaupro

    2
    0
    Aug 8, 2011
    Metal detector coil amplifier

    Hello!
    I can help someone with a scheme to enhance signal reception, a metal detector search coil for total, operating with 14 kHz?
    Bs Reg.
     
  3. camerart

    camerart

    85
    2
    Aug 18, 2010
    Hi Bereaupro,

    Can you clarify please?

    Cheers.
     
  4. bureaupro

    bureaupro

    2
    0
    Aug 8, 2011
    I have a Metal detector White's M6 and I want to increase the depth performances,amplifying the signal reception of coil search.I want a schematic something like this:.I mention the detector working with 14 khz.
     
  5. duke37

    duke37

    5,341
    753
    Jan 9, 2011
    I do not know what a coil amplifier is but your circuit seems to have some strange details.
    1. There is a 1k resistor across the power supply, this just takes power to no pupose.
    2. The first op-amp provides a voltage reference for the other two amps. This feeds a capacitor and a 1k to ground. You would be better moving the capcitor to the input and eliminating the 1k to ground (see 1).
    3. There is no power supply smoothing, An electrolytic between Vcc and GND would do no harm.
    4. The outputs have 100n capacitors referenced to Vcc, It would be better to reference these to GND especially in view of 3.
     
  6. camerart

    camerart

    85
    2
    Aug 18, 2010
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