Short Beep Tone with LM555

Discussion in 'The Projects Forum' started by Belteshazzar, Apr 13, 2010.

  1. Belteshazzar

    Thread Starter Member

    Mar 16, 2010
    34
    0
    Could someone help me finalize this project of mine?

    I have found several beep circuits using the 555 but none to do what I need.

    Attached is a schematic I found earlier, placed by Bernard and/or Sgt Wookie if I am not mistaken.

    It works great, I played with the resistors turning R1 to 10K and R2 to 47k and it turns into a nice constant short beep alert tone...in case anyone is interested to build it.

    I built it without the 2N2222A, just the right side of the schematic feeding it 5V.

    Can I change this circuit somehow to do the following?


    - Pressing a momentary push-button I get only a short beep that terminates after a fraction of a second EVEN if I keep the push-button pushed.

    - Then, when you let go of the button and push it again its ready to do another short beep.....as quickly as I can press the button.

    - Assuming the push button is NOT the also the power-on button; the 555 will be already on via a 5V supply.


    ....through a charge and discharge of a lytic cap maybe?

    Thanks
     
    Last edited: Apr 13, 2010
  2. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    The 555 can be set up as a one-shot, Your momentary button could trigger the pulse.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
  4. Belteshazzar

    Thread Starter Member

    Mar 16, 2010
    34
    0
    Ratched, I'm sorry but I don't understand how to put it together, can you draw me a shematic using the 555 as one "one shot"?

    Bill, I went through your circuits, I didn't see one that does what I described!

    Maybe it was right in front of me, but I don't know how to recognize the circuit and/or make modifications to my specs!

    Can you draw one up?
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    The monostable is what you described. I'll show how to connect a pushbutton when I get a chance.

    How long do you want the beep to last?
     
  6. Belteshazzar

    Thread Starter Member

    Mar 16, 2010
    34
    0
    About 1/4 of a second

    or to make it simple, under a second
     
    Last edited: Apr 13, 2010
  7. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    You will note this schematic was very slightly modified from the one in 555 Monostable. You should read the article to understand how it works.

    [​IMG]
     
  8. Belteshazzar

    Thread Starter Member

    Mar 16, 2010
    34
    0
    Thank you, Bill, it works PERFECTLY. This is exactly what I needed.

    I changed the 10uF lytic cap to a 2.2uf to get a shorter beep, though.


    I do have a problem, however, trying to find what pizzo speaker works with this circuit.

    I only have one pizzo element that I found in another electronic gadget of mine and I don't know exactly what it is or where to buy it.

    I got lucky and plugged it in the circuit I posted and it worked...it also works with your circuit.
    I do not want to get lucky and 'happen" to find a pizzo that works.
    I would like to have it fully identified and know where to buy it in case I want to duplicate this circuit.

    The pizzo I have that works is labeled "WST-1206UX". There is also a "-P" and the + symbol. Its resistance is 175M.

    The two giants, mouser.com and digikey.com don't have it.


    Beforehand I had ordered a few pizzos from Mouser and nothing worked, only this one that I found laying around.

    What is the 'Sonalert'. I have seen this posted on other projects too.
    Does it have a built in oscillator?

    Do you have a part# so that I can buy it from mouser or digikey?

    Thanks again for the circuit!
     
  9. Belteshazzar

    Thread Starter Member

    Mar 16, 2010
    34
    0
    Never mind....I found the info.

    It's a regular piezo buzzer 3V-12V. Has the drive built-in. Just give it power and it sounds.

    Thanks again for everthing!
     
Loading...