Connect with us

Metal detector circuit help.

Discussion in 'General Electronics Discussion' started by Shyamal796, Mar 25, 2012.

Scroll to continue with content
  1. Shyamal796

    Shyamal796

    32
    0
    Mar 19, 2012
    I am trying to make metal detector circuit. Here used 555 timer ic which diagram i found one website. as circuit diagram i connect all component but raise alarm all time. But why without metal, inductance is produced frequency?
     
  2. timothy48342

    timothy48342

    218
    0
    Nov 28, 2011
    Can you post the schematic or a link to it or a link the the website?
    -t
     
  3. shrtrnd

    shrtrnd

    3,701
    462
    Jan 15, 2010
    Is your sensing coil near something metal while you're testing this?
     
  4. Shyamal796

    Shyamal796

    32
    0
    Mar 19, 2012
  5. Shyamal796

    Shyamal796

    32
    0
    Mar 19, 2012
    No, it is far from metal.
     
  6. shrtrnd

    shrtrnd

    3,701
    462
    Jan 15, 2010
    I know you probably already did, but recheck your wiring. Do not assume something
    is right, seriously look at the circuit again one more time. Often I find I made a simple
    wiring mistake and then ignored it while troubleshooting because I dismissed it from
    my mind. Do you have the correct capacitance for your capacitors ufd and not pfd,
    Is is possible you damaged your LM555, and are now just assuming it is ok when it might not be.
    Try not to get frustrated, and take some time to recheck everything carefully one more time.
     
  7. twister

    twister

    172
    7
    Feb 12, 2012
    That circuit is supposed to make noise all the time. When you move the coil close to metal you should hear a change in frequency. A larger diameter coil should be more sensitive.
     
  8. Raven Luni

    Raven Luni

    798
    7
    Oct 15, 2011
    I was actually going to experiment with making one of those tonight. It's been years since I read this stuff but a friend has use for one so I'll need to quickly brush up but if I remember what you're actually picking up is a disturbance in the electric field (not the magnetic field) of an inductor caused by motion relative to a piece of metal which can be either ferromagnetic (iron etc) or paramagnetic (copper, aluminium etc).

    Anyway, you'd probably start with an AC voltage at an audible frequency giving you a continuous tone which wobbles when you pass over something that disturbs the field (this is what you listen for, not the tone itself).

    So when you say 'raising the alarm' do you mean the continuous tone?
     
  9. twister

    twister

    172
    7
    Feb 12, 2012
    I have heard of people making a huge coil, and then they tow it behind a ATV, and they use it to find meteors. I guess they are worth a lot of money.
     
  10. davenn

    davenn Moderator

    13,497
    1,830
    Sep 5, 2009
    Yup, exactly

    So to the OP, Were you hearing a continuous tone from the speaker, that changed in frequency (pitch) when some metal was brought near the coil ??

    Dave
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,300
    2,737
    Jan 21, 2010
    It depends what you mean by sensitive.

    From memory, a larger coil will detect larger pieces of metal at longer distances, but may be less affected by small pieces of metal close to it. Conversely, a smaller coil will be sensitive to small pieces of metal close up, but insensitive to relatively large pieces further away.

    Most people are after sensitivity to small items further away
     
  12. Shyamal796

    Shyamal796

    32
    0
    Mar 19, 2012
    I have same problem.
     
  13. surajsasi.mvk

    surajsasi.mvk

    1
    0
    Mar 15, 2013
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-