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Cd4033 - 555 timer frequency counter..

Discussion in 'General Electronics Discussion' started by ian moree, Mar 6, 2017.

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  1. ian moree

    ian moree

    6
    2
    Mar 6, 2017
    Good day everyone;

    i have built this circuit and no matter what i do, i am unable to read frequencies from known sources.

    Perhaps the circuit itself is incorrect? i would appreciate any guidance one has to offer.

    thank you

    -ian

    upload_2017-3-6_12-48-47.png
     
  2. Alec_t

    Alec_t

    2,935
    799
    Jul 7, 2015
    Welcome to EP.
    I see nothing obviously wrong with the circuit.
    Are the displays showing anything?
    Is your input signal amplitude at least 1V?
    Check that :-
    pins 16 of all 4033s are at the correct supply voltage,
    pins 3 of both 555s, and the collectors of T1 and T2 are all toggling.
     
  3. davenn

    davenn Moderator

    13,786
    1,936
    Sep 5, 2009
    Hi Ian,
    Welcome to EP :)

    where did the circuit come from please link to it ... so we can see any circuit descriptions etc


    Dave
     
  4. ian moree

    ian moree

    6
    2
    Mar 6, 2017
    DIsplays are Showing all Zeros
    signal amplitude is 2.163 volts
    correct 5.5v at pins 16,3 on 4033
    **dont know how to test T1 , T2 toggle
     
  5. Alec_t

    Alec_t

    2,935
    799
    Jul 7, 2015
    What measuring instruments do you have access to?
    Do the LEDs light/flash?
     
  6. ian moree

    ian moree

    6
    2
    Mar 6, 2017
    Analog OScope, Digital Multimeter(fluke, and more ), sinometer, LC METER,

    The led's are lighting up but not blinking.
     
  7. Alec_t

    Alec_t

    2,935
    799
    Jul 7, 2015
    LED1 and LED2 should be flashing alternately, with a period of ~4.6S and an 'on' time of ~2.3S. As this is not the case, check all pin connections to both 555s and ensure they are getting 5V on pins 4 and 8. If the 555s are socketed, make sure you have the ICs the right way round in the sockets.

    Edit:
    This probably has no bearing on your immediate problem, but one thing I don't like about that circuit is that when pin 3 of IC2 goes low, cap C6 applies a negative 5V pulse to pins 15 of the 4033s. I'm not sure they'll like that. Personally I'd clamp that pulse with a diode (anode to ground, cathode to C6/R12 top).
     
    Last edited: Mar 7, 2017
  8. Audioguru

    Audioguru

    3,116
    696
    Sep 24, 2016
    The old 555 ICs draw a 400mA spike from the supply each time they switch. Therefore the datasheet spells out two very important supply bypass capacitors that are missing in this bad circuit. I think Cmos 555s should be used.
     

    Attached Files:

  9. ian moree

    ian moree

    6
    2
    Mar 6, 2017
    Unfortunately , this is the only schematic i can find with components i currently have. If any of you have another schematic which can help me, then that would be awesome. Thanks with everything. will check...
     
  10. Audioguru

    Audioguru

    3,116
    696
    Sep 24, 2016
    Simply look at the datasheet of the 555 and order and connect the supply bypass capacitors that are recommended.
    The old project in the Electronics For You website is from India.
     
  11. ian moree

    ian moree

    6
    2
    Mar 6, 2017
    I took out and tested every IC -4033 & 555 timers and 2 out of the 5 4033's in circuit came from Mouser Dead. Thanks for all your help, now that i have functioning 4033's the circuit works flawlessly with bypass caps for pins 4 & 8 of the 555 timer connected. thank you all for your help!!
     
    davenn and Arouse1973 like this.
  12. Alec_t

    Alec_t

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    799
    Jul 7, 2015
    Good to hear you've got it working.
     
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