555 timer dog whistle help

Discussion in 'The Projects Forum' started by MDaines, Nov 4, 2011.

  1. MDaines

    Thread Starter New Member

    Aug 13, 2010
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    I'm trying to build an ultrasonic dog whistle but am an absolute noob when it comes to reading schematics. I've breadboarded the circuit but I can't get it to work. Attached is a pic of my breadboard and wonder if anyone can tell me where I'm going wrong? Thanks for giving an eager newbie a hand.
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    The 555 and I are old friends. I have written a set of tutorials on using them, complete with drawings similar to yours.

    I'll review them in more detail when I have time (in a couple of hours). Meanwhile, you might take pictures of your work and post it, we might spot something you missed.

    Bill's Index

    The 555 Projects

    A different variation, not quite what you have but very similar.

    555 Hysteretic Oscillator
     
    Last edited: Nov 4, 2011
  3. jimkeith

    Active Member

    Oct 26, 2011
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    You have your proto board screwed up

    Pins 2 must be jumpered to pin 6
    Right side of pot does not go to common

    10uf coupling cap prob not required as piezo device is open circuit for DC
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    OK, 2 and 6 are not connected, as mentioned.

    Pin 7 is not switched as per your schematic.

    You really should have the battery connected directly to the switch, and the switch feeds the power supply buss. This would simplify some of your wiring.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Along with everything else mentioned, you have connected your 10uF cap backwards; the stripe on the side of the package indicates the negative side. If you connect an electrolytic cap backwards, you will destroy it very quickly.
     
  6. iONic

    AAC Fanatic!

    Nov 16, 2007
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    So, without a REAL picture, all suggestions may be mute as your skills at using the breadboard program may be lacking.

    Also, if the circuit is working fine the frequency is as high as 22kHz, you will never know that it is working. You won't be able to hear it. But a dog might. But don't go sticking it up to his ear to try it either.
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    Your breadboard photo shows a 4kHz piezo beeper that has a built-in oscillator and runs from a DC voltage.
    You need a piezo transducer (it is a speaker). The article used a piezo horn tweeter.
    Do not use an ordinary piezo transducer that is in a package tuned to resonate loudly at 4kHz.
     
  8. MDaines

    Thread Starter New Member

    Aug 13, 2010
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    I live on the other side of the world and it's amazing to wake up to so many people trying to lend a hand! Thank you all for your kindness.

    I've taken everyone's suggestions on board and managed to wake my dog up from his morning nap. :D ... Don't worry, I have my dog's interests close to my heart and plan to use this to play a game of hide and seek with him. Attached is a (real) pic of my working circuit.

    Out of curiosity, how do I tell what frequency it's playing?
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    You could find a friend with a DVM that has a freq counter on it, or buy one. If you have access to an Oscope that would do it too.
     
  10. MDaines

    Thread Starter New Member

    Aug 13, 2010
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    Thanks Bill and everyone for all their help.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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    Try adding another 10nF cap in parallel to the one you have in there.
    The frequency output should be roughly 1/2 the original frequency.
    You can compare that sound to various tones to find the frequency.
     
  12. Wendy

    Moderator

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    Side note: it also works on teenagers, at a slightly different frequency. When I was in college 37 years ago we had a lot of fun with ultrasonics and driving people crazy.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    When I was a teenager, the sound of the television HV supply drove me nuts. I couldn't understand why it didn't bother my folks.

    Working on supersonic fighter aircraft that had afterburners (F-4J Phantom II's) cured that little problem pretty quickly.
     
  14. Wendy

    Moderator

    Mar 24, 2008
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    Yeah, it did it for my Dad too (air force mechanic). It obviously bothered him, so he denied it. I figured out pretty quickly he couldn't hear specific frequencies.
     
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