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555/556 Timer Circuit

Discussion in 'Electronic Basics' started by DaveK, Feb 10, 2007.

  1. DaveK

    DaveK Guest

    I'm kind of new to this electronics stuff. I took a class years ago
    and have a pretty good idea of how basic circuits work. I don't have a
    clue about IC's.

    I am working on a little project which I don't know how to set up. I
    am using a 4.5VDC battery power source with a mercury switch that will
    be used to close the circuit and sound a buzzer. What is happening is
    that when the circuit closes the mercury will continue to slosh around
    and sound the buzzer multiple times. What I would like to happen is
    when the circuit closes it sounds the buzzer for a split second, opens
    and stays open for a determined amount of time (3sec) even if the
    mercury closes the circuit again. I was told I could use a 555 or 556
    timer to accomplish that. I purchased both timers and set up a couple
    basic circuits that I saw on the internet. I've played around with the
    timers for a long time but I just can't figure out how to use them to
    accomplish my above goal.

    I would surely appreciate any information or what I would need to
    purchase to get my circuit working. If you have any questions I would
    be happy to answer them. You can reach me by e-mail
    or phone 480-763-8199.

    Thanks for Your Time,

    Dave Kofka
     
  2. Bob

    Bob Guest

    Dave,

    It would help if you could provide a link to the circuit you're using, or
    post the schematic in alt.binaries.schematics.electronic . It should be easy
    figure out why it's not working.

    The basic idea would be to use the first 555 to immediately fire and drive
    the buzzer. This first 555's output would also fire the second 555. The
    first 555 would timeout quickly and stop the buzzer. The second timer would
    have a longer delay (3 seconds) and would inhibit refiring of the first 555
    until the 3 seconds elapsed.

    There may be a tricky way to do it with a single 555 but using two (or a
    556) would be easier.

    Bob
     
  3. John Fields

    John Fields Guest

    ---
    View in Courier:
    CR1
    .. +------------------[<1N4148]--------------------+
    .. | |
    ..+V---+---------+--|--+-------+---------------+-----+-------+ |
    .. | R1 R2| | | |8 R3| | |8 |
    .. [10K] [10K]|[Rt1] +---+---+ [10K] [Rt2] +---+---+ |
    .. | | | | 2|_ Vcc |3 C2 | | 2|_ Vcc |3 |
    .. +-[0.1µF]-+--+--|--O|T OUT|-+-[0.1µF]-+-----|--O|T OUT|--+
    .. | C1 | 6| | | | 6| |
    .. | O +---|TH | +----+ +---|TH |
    .. | O S1 | 7|_ 555| | | 7|_ 555|
    .. | +--O|D | | +--O|D |
    .. | | | GND | [BUZZER} +| | GND |
    .. | [Ct1] +---+---+ | [Ct2] +---+---+
    .. | | U1 |1 | | U2 |1
    ..GND--+---------------+-------+----------+----------+-------+



    When S1 closes it pulls the junction of R1 and C1 to ground, which
    generates a momentary low going pulse at U1-2, the TRIGGER- input of
    U1. This causes U1-3 to go high for:


    Tout = 1.4 Rt1 Ct1


    during which time the buzzer will sound.

    When U1 times out, U1-3 will go low, generating a low-going pulse at
    U2-2, which will cause U2-3 to go high for:


    T = 1.4 Rt2 Ct2

    When U2-3 goes high it will force U1-2 high and keep any extraneous
    contact closures of S1 from triggering U1. When U2 times out it
    will be disconnected from U1-2 by CR1 and the next S1 contact
    closure will start the cycle anew.
     
  4. John Fields

    John Fields Guest

    ---
    I left out a couple of diodes.

    Here's the LTSPICE circuit list:


    Version 4
    SHEET 1 1972 1056
    WIRE 96 16 -448 16
    WIRE 208 16 160 16
    WIRE 240 16 208 16
    WIRE 416 16 320 16
    WIRE -672 80 -832 80
    WIRE -560 80 -672 80
    WIRE 16 80 -560 80
    WIRE 288 80 16 80
    WIRE 416 80 416 16
    WIRE 416 80 288 80
    WIRE 736 80 416 80
    WIRE -672 112 -672 80
    WIRE -560 112 -560 80
    WIRE 288 128 288 80
    WIRE -272 160 -336 160
    WIRE 16 160 16 80
    WIRE 16 160 -48 160
    WIRE 112 160 16 160
    WIRE 448 160 384 160
    WIRE 736 160 736 80
    WIRE 736 160 672 160
    WIRE 832 160 736 160
    WIRE 112 192 112 160
    WIRE 832 192 832 160
    WIRE -672 224 -672 176
    WIRE -560 224 -560 192
    WIRE -560 224 -672 224
    WIRE -368 224 -560 224
    WIRE -272 224 -368 224
    WIRE 16 224 -48 224
    WIRE 208 224 208 16
    WIRE 288 224 288 192
    WIRE 288 224 208 224
    WIRE 448 224 288 224
    WIRE 736 224 672 224
    WIRE -672 256 -672 224
    WIRE -448 288 -448 16
    WIRE -272 288 -448 288
    WIRE 16 288 16 224
    WIRE 16 288 -48 288
    WIRE 448 288 272 288
    WIRE 736 288 736 224
    WIRE 736 288 672 288
    WIRE 16 320 16 288
    WIRE 112 320 112 272
    WIRE 112 320 16 320
    WIRE 736 320 736 288
    WIRE 832 320 832 272
    WIRE 832 320 736 320
    WIRE -832 352 -832 80
    WIRE -304 352 -832 352
    WIRE -272 352 -304 352
    WIRE 112 352 112 320
    WIRE 448 352 416 352
    WIRE 832 352 832 320
    WIRE -832 432 -832 352
    WIRE -672 432 -672 320
    WIRE -448 432 -448 288
    WIRE -304 432 -304 352
    WIRE 416 432 416 352
    WIRE 416 432 -304 432
    WIRE -368 496 -368 224
    WIRE -112 496 -368 496
    WIRE 272 496 272 288
    WIRE 272 496 -48 496
    WIRE -832 544 -832 512
    WIRE -672 544 -672 512
    WIRE -672 544 -832 544
    WIRE -448 544 -448 512
    WIRE -448 544 -672 544
    WIRE -336 544 -336 160
    WIRE -336 544 -448 544
    WIRE 112 544 112 416
    WIRE 112 544 -336 544
    WIRE 384 544 384 160
    WIRE 384 544 112 544
    WIRE 832 544 832 416
    WIRE 832 544 384 544
    WIRE -832 592 -832 544
    FLAG -832 592 0
    SYMBOL Misc\\NE555 -160 256 R0
    SYMATTR InstName U1
    SYMBOL voltage -672 416 R0
    WINDOW 3 24 104 Invisible 0
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR Value PULSE(4.5 0 .1 1e-6 1e-6 .01 .05)
    SYMATTR InstName V1
    SYMBOL voltage -832 416 R0
    WINDOW 123 0 0 Left 0
    WINDOW 3 24 104 Invisible 0
    SYMATTR Value 4.5
    SYMATTR SpiceLine Rser=0
    SYMATTR InstName V2
    SYMBOL res 96 176 R0
    SYMATTR InstName R2
    SYMATTR Value 1e6
    SYMBOL cap 96 352 R0
    SYMATTR InstName C1
    SYMATTR Value .5e-6
    SYMBOL Misc\\NE555 560 256 R0
    SYMATTR InstName U2
    SYMBOL res 816 176 R0
    SYMATTR InstName R4
    SYMATTR Value 1e6
    SYMBOL cap 816 352 R0
    SYMATTR InstName C2
    SYMATTR Value 5e-6
    SYMBOL res 336 0 R90
    WINDOW 0 -33 60 VBottom 0
    WINDOW 3 -27 58 VTop 0
    SYMATTR InstName R5
    SYMATTR Value 10k
    SYMBOL cap 96 32 R270
    WINDOW 0 69 32 VTop 0
    WINDOW 3 66 35 VBottom 0
    SYMATTR InstName C3
    SYMATTR Value .1e-6
    SYMBOL cap -656 320 R180
    WINDOW 0 24 64 Left 0
    WINDOW 3 24 8 Left 0
    SYMATTR InstName C6
    SYMATTR Value .1e-6
    SYMBOL res -576 96 R0
    SYMATTR InstName R6
    SYMATTR Value 10k
    SYMBOL res -464 416 R0
    SYMATTR InstName R1
    SYMATTR Value 100
    SYMBOL diode -48 480 R90
    WINDOW 0 0 32 VBottom 0
    WINDOW 3 32 32 VTop 0
    SYMATTR InstName D1
    SYMATTR Value 1N4148
    SYMBOL diode -656 176 R180
    WINDOW 0 46 30 Left 0
    WINDOW 3 24 0 Left 0
    SYMATTR InstName D2
    SYMATTR Value 1N4148
    SYMBOL diode 304 192 R180
    WINDOW 0 -41 35 Left 0
    WINDOW 3 -73 0 Left 0
    SYMATTR InstName D3
    SYMATTR Value 1N4148
    TEXT -808 568 Left 0 !.tran 0 10s 0
     
  5. roma

    roma Guest

    See these delay circuits at :http://members.shaw.ca/roma/eighteen.html
     
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