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Clap switch confusion!

Discussion in 'General Electronics Discussion' started by ObviousOllie, Feb 15, 2017.

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  1. ObviousOllie

    ObviousOllie

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    Feb 15, 2017
    I have a clap switch project for my college, I have meticulously looked over the diagram and alas nothing has come of it. I shall need some assistance from whomever sees this, I would be grateful. Thanks... DSC_0018.JPG DSC_0017.JPG Clap-Switch-Circuit-Diagram1.jpg
     
  2. duke37

    duke37

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    Jan 9, 2011
    What is wrong?
    You need diodes across the relay coils to protect T2, T3 and T4 from induced voltages.

    Have you got it wired correctly I do not see R7, R8 and R9. Not that it matters. There seems to be many connections from T2,T3 and T4 to +5V. Are you putting too much current through the transistors?
     
  3. ObviousOllie

    ObviousOllie

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    Feb 15, 2017
    I removed r7 r8 and r9 along with the relays because I'm not using mains access and the resistora don't do anything vital.
     
  4. duke37

    duke37

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    771
    Jan 9, 2011
    You have not said what is wrong.:rolleyes:
    If nothing works, then split the circuit between the chips and check the stages individually.
    Do you have enough voltage? 5V into the 4017 will give less than this out, check the data. There will be 0.6V lost in the transistor, you have not said what voltage the leds need.
     
  5. ObviousOllie

    ObviousOllie

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    Feb 15, 2017
    The LEDs need around 5v to function but will still light at less. I don't know what it wrong with it but obviously when I clap, nothing happens
     
  6. AnalogKid

    AnalogKid

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    Jun 10, 2015
    1. There is no decoupling of anything anywhere. Add a 100 uF electrolytic and 0.1 uF ceramic in parallel across the two power rails where the red and black wires enter. Add a 0.1 uF ceramic cap across IC1 pins 1 and 8 and IC2 pins 8 and 16.

    2. Disconnect IC1 pin 3 from IC2. Add an LED and 220 ohm resistor in series from IC1 pin 3 to GND. Clap. Observe. Report. If the LED does not flash, the problem is in the 555 circuit. Debug.

    3. If the 555 circuit is working, reconnect it to IC2, remove T2, T3, And T4, and connect the cathodes of the three LEDs to GND. This should show if the counter is advancing.

    Given that the circuit does not work and you can't figure it out, I don't think you are in a position to proclaim what is and is not vital. They prevent IC2 from burning up due to overcurrent stress of the output transistors. What is the forward conduction voltage (Vf) of the LEDs?

    ak
     
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  7. ObviousOllie

    ObviousOllie

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    Feb 15, 2017
    I can only work in it on Wednesdays, so I'll get back to you if it works, thanks!
     
  8. ObviousOllie

    ObviousOllie

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    Feb 15, 2017
    I don't know vf of the leds, the box just describes "white LED"
    I am extremely new to electronics. The course literally throws us into a project where they haven't taught us timers or counters yet, I've tried my best to find out how to use them but it's very confusing...
     
  9. AnalogKid

    AnalogKid

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    Jun 10, 2015
    In a quiet room, look at the collector of T1 and report its voltage. Hopefully it is sitting near 5 V.

    ak
     
  10. davenn

    davenn Moderator

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    Sep 5, 2009
    The LEDs shouldn't be in the Base cct of the transistors .... they wont work there
     
  11. AnalogKid

    AnalogKid

    2,501
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    Jun 10, 2015
    A 4017 can make 4 mA, granted at a sagging Vout. That should be enough to see something if the diode Vf isn't too high. I'd change to a standard little green LED and reduce the base resistors.

    ak
     
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