Sensor Sub System

Discussion in 'General Electronics Chat' started by onceinalifetim, Mar 7, 2014.

  1. onceinalifetim

    Thread Starter New Member

    Feb 9, 2014

    I'm trying to learn and hope you guys have the patience with me..
    I am currently working on a autoguilded vechile project, the vehicle consists 3 parts, 2 Inductive sensors, motor driving and steering and control unit pic, and my job for the project is doing the sensor sub system..

    The overall project is like this:

    A vehicle will follow a track which consists of a continuous loop of wire carrying a current of ~140mA (RMS) at a frequency of 10kHz

    Appropriate values for the parallel resonant circuit C1 and C2, the high pass cut off C3 & C4, an amplifier gain of 100 (R1) and the low pass cut off C7 & C6.

    The range of the freq that i set is 9.5khz to 10.5khz.

    i have attach the pic to it , please take time to take a look..

    C1 = 330nf
    C2 = 470nf

    C3 = 68nf
    C4 = 22Nf

    C7 = 470pf
    C6 = 220pf

    C5 & C6 = 100nf

    R3 = 1K
    R2 = 680
    R1 = 100K

    OP AMP = LM324

    I have use the breadboard to test the circuit. after setting up the circuit, i have used the oscilloscopes to check the voltage output, i do have a pure sine wave, but whenever i increase the freq, it clip off the top and bottom of the sine wave.. may i know how to solve the problem???

    i trying to learn..
  2. russ_hensel

    Distinguished Member

    Jan 11, 2009
    The clipping is from too much gain in the circuit, this is what started HP they
    figured out how to stabilize the amplitude of their circuit using the filament resistance
    of a low voltage bulb.

    Your circuit looks difficult to tune other forms of an oscillator may be easier, I like the quadrature ossc. which takes a couple of op amps to implement but has no inductors and is easy to tune.

    In some ossc. diodes are used with resistors to give soft clipping of the wave, adjustment of the gain is not so difficult.

    How are you going to get to 140 ma, it is much more than a lm324 is going to give you.

    You can use an emitter follower ( push pull ) for more current or a little integrated audio amp. Keep the power part away form the ossc. or you may have even more instablilty in either frequency and/or wave shape.
  3. #12


    Nov 30, 2010
    I think the schematic is the pickup, not the driver. It needs the coil to pick up the signal.
  4. onceinalifetim

    Thread Starter New Member

    Feb 9, 2014
    to russ_hensel..

    the car will follow the track, and it will produce 10khz to let the sensor sense it...

    it is possible to change the ic chip???
  5. onceinalifetim

    Thread Starter New Member

    Feb 9, 2014
    and may i know how to know the gain of the circuit??