problem with a circuit

Discussion in 'General Electronics Chat' started by mubwandaz, Apr 2, 2015.

  1. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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    hie guys.i am trying to build a circuit but i am not good at electronics . i am trying to convert pwm of a hall sensor to a voltage out put using a lm2917 tacho chip,then measure the frequency and voltage using an oscilloscope and plot the results on a graph.is it possible to measure these both at the same time.i am using a circuit diagram i found on line but the circuit seems not to be working
    thank you
     
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  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Without knowing exactly how you have built this, how could anyone even begin to guess as to why it doesn't work. The circuit appears to be from the datasheet, so it should be ok.

    Yes, it is possible to measure voltage and frequency at the same time.
     
  3. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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    I am building it on a bread board and using the same circuit diagram I found on line of the lm2917 and added a Hall Effect sensor to the circuit. Similar to the diagrams above
     
  4. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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  5. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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    Also then tried it on a strip board
     
  6. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Verify component polarity and values.
    Inspect every solder joint.
    Check there are no shorts, especially between the copper tracks.
    Use a meter to confirm that everything connects exactly where it should and nowhere else.

    This is all part of the troubleshooting process that you must learn to do by yourself before seeking assistance. Electronics is an exact science and attention to detail is an essential skill.
     
    Last edited: Apr 3, 2015
  7. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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    I have checked all tracks. Even used a multi meter to double check connections etc. Maybe I am connecting it wrong to the scope have both probes on output of the chip but have channel one reading voltage and channel two reading frequency
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    your chip is in the wrong way, pins 1,2 have a link in , they should be on pins 5,6.

    You have maybe blown the ic up by connecting it backwards.
     
  9. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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    5-6 are connected .on pin 1-6 i have put a pull up resistor
     
  10. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    The chip is in the wrong way round, !!!!!!
     
  11. mubwandaz

    Thread Starter New Member

    Apr 2, 2015
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    I put it the right way after,just before testing . but I had taken the pic already
     
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