ir led and phototransistor Simulation

Discussion in 'The Projects Forum' started by OSOO, Mar 28, 2014.

  1. OSOO

    Thread Starter Member

    Feb 19, 2014
    34
    0
    Hi,





    I'm working on circuits of the iv infusion ,and now I want to simulate the circuit of drops counter using isis proteus v7.10



    this is my circuit design which I posted previously in this forum:

    [​IMG]




    now ,I've drawn the circuit in isis proteus, but I couldn't find the ir led and the phototransistor ,so I used a pulse signal generator as you can see:




    [​IMG]


    is this way useful to simulate the drops counter circuit ?


    also I want to ask about how to measure or visualize the voltage at any point on the circuit with isis program ?
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,539
    1,251
    I'm not familiar with proteus, but I have some comments on your circuit.

    A 741 does not swing down low enough to reliably signal the input of a microcontroller. You will have to use something like an LM358. One 358 can replace both 741s.

    After the first pulse, the first amp will lock up. Your input transistor pulls the input high, but when it turns off there is nothing to pull the input low. First pass - connect the Q1 collector directly to VCC, and connect R2 from Q1 emitter to GND.

    ak
     
    OSOO likes this.
  3. DickCappels

    Moderator

    Aug 21, 2008
    2,653
    632
    One thing that pops out right away is that if U1 is intended to be an amplifier instead of a Schmitt trigger, you need to swap the inverting and noninverting inputs of U1. You might also find that the 2k feedback resistor does not give you enough gain.

    Also, you should connect the noninverting input of U1 to the voltage divider that biases U2 so that the output of U1 can swing negative with respect to the noninverting input.

    Theoretically, you don't need R2 or R4.
     
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  4. OSOO

    Thread Starter Member

    Feb 19, 2014
    34
    0
    I removed R4 but nothing new , not working !

    I put a 555 timer ,triggered via the comparator output pin ,and now the counter is working ,is this a good solution :) ?
     
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