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creating a two stage alarm siren

Discussion in 'General Electronics Discussion' started by Shizzles, May 26, 2010.

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  1. Shizzles

    Shizzles

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    May 26, 2010
    I am attempting to design an alarm using a LM555 timer. I dont know where to start. My friends around have been designing them and I am trying to make one of my own. HELP! where do i start? what should the simulations look like?!? The others seem to generate a waveform that rises constantly and then starts pulsating. how do i do this with mine?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Perhaps you start with google. (555 alarm schematic)
     
  3. Shizzles

    Shizzles

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    0
    May 26, 2010
    i did. didnt get very far. i have tried simulating some of the circuits from google but i dont seem to be getting any output.. any other suggestions?!
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Show us the circuit you are trying to simulate.
     
  5. Shizzles

    Shizzles

    3
    0
    May 26, 2010
    i'm trying to get a pulse wave from a lm555 timer with a duty cycle of 50%(astable vibrator) as a first step..but my simulation program the circuit maker just give me a straight line as the wave form...
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,499
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    Jan 21, 2010
    Show us the circuit
     
  7. atta1

    atta1

    5
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    Apr 20, 2012
    Hi guys
    I have the same question as Shizzles. I have the output waveform with me, but dont know how to upload the image as everytime when I click on upload image it wants me to provide an URL but the image is on my laptop desktop.
    Using 4 LM555 timers (or two lm556), the output should be a line that rises 45 degrees starting at zero as phase one then change over to a square wave as phase two and repeat the cycle of triangle/sqaure.
    If somebody can help me with uploading images then I can show you guys exactly what I mean

    Thanks in advance
     
  8. davenn

    davenn Moderator

    13,883
    1,966
    Sep 5, 2009
    hi atta1
    welcome to Electronics Point

    re file uploads... if you look down below a message you are typing to post, there are 2 buttons Post Quick Reply and Go Advanced

    when you click on the go advanced it gives more oprions below you text window, one of which is a button.. Manage Attachments. when you click on that it will open a smaller window that lets you upload images / files from your computer

    Now some NOTES....
    1) ... if you are taking photos of circuit boards etc for us guys to look over for faults etc do sharp well lit images
    2) reduce the physical size of the image so that they are preferably 700x500 pixels or less
    3) compress the images a bit and try to keep the max kb size to ~ 100kb

    cheers
    Dave
     
  9. atta1

    atta1

    5
    0
    Apr 20, 2012
    Hi Dave
    Thank you so much for your help so far.
    I have attached two images. The one is the output waveform what we should be getting after setting everything up. The other is the schematic we have been provided with.

    T1 is a monostable “one shot” multivibrator circuit using one LM 555. Once S1 turns on,
    T1 should produce an active low pulse after 3 minutes, hereby resetting T2.

    T2 is an astable multivibrator using one LM 555 generating a square wave, duty cycle =
    50 %, T = 2 s. When the output of T2 is active high, it immediately charges capacitor C1
    through the diode. When the output of T2 is low, the diode is reverse biased and C1
    discharges through R1. This voltage controls T3 the tone frequency of T3.

    T3 works as a voltage controlled oscillator. Because of the low impedance at the control
    pin of the LM 555 used in T3, a buffer circuit should be used between the control pin and
    R1-C1. This buffer can be a straightforward emitter follower.

    T4 is an astable multivibrator (using one LM 555), generating a 5 Hz square wave, duty
    cycle = 50 %. This circuit toggles the enable pin of the 555 timer used in T3 (HINT: the
    enable pin of a LM 555 is active low).

    I am busy creating T1 at the moment using LTspice and I plan to create T1-T4 using spice and then connecting it all together and hopefully getting what I want.

    Thanks in advance for all the help

    Atta1
     

    Attached Files:

  10. davenn

    davenn Moderator

    13,883
    1,966
    Sep 5, 2009
    no probs
    As steve said above show us some circuit diagrams
    as you say you are designing the various circuits at the moment,when you get the schematics layed out post them up here :)

    cheers
    Dave
     
  11. atta1

    atta1

    5
    0
    Apr 20, 2012
    Attached is my circuit for T1 by itself. When I ran it using LTspice it didn't work but I think that will be due to no battery (we have to use a 9V). This circuit is purely a monostable “one shot” multivibrator
     

    Attached Files:

    • T1.gif
      T1.gif
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  12. atta1

    atta1

    5
    0
    Apr 20, 2012
    Attached is my T2 astable multivibrator. Can I assume that output from T1 feeds into the input from T2?

    Atta1
     

    Attached Files:

  13. atta1

    atta1

    5
    0
    Apr 20, 2012
    Hi guys

    The image below is pretty close to what I want, but I need to use 4 LM555/NE555 or 2 LM556/NE556. Where would I plug in the last IC?

    Atta1
     

    Attached Files:

  14. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    You do not say what you want!

    Ground connections seem to be getting closer to ground, that is good..

    IC3 has no power.

    IC2 and IC3 are fighting for the output, this is not good.
     
  15. davenn

    davenn Moderator

    13,883
    1,966
    Sep 5, 2009
    nor does IC 2 instead its power pins are tied to the output (pin3) of IC1
    that isnt going to supply an operating voltage for IC2

    Dave
     
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