Light Gate With Counter Using 555 And 4033


Posted on Feb 5, 2014

The circuit described here counts the number of times that an infrared beam is interrupted. It could be used to count the number of people entering a room, for instance, or how often a ball or another object passes through an opening (handy for playing shuffleboard). The heart of the circuit consists of - you guessed it - a light gate! Diode D1 is


Light Gate With Counter Using 555 And 4033
Click here to download the full size of the above Circuit.

an IR diode that normally illuminates IR transistor T1. The light falling on T1 causes it to conduct to a certain extent. The resulting voltage on the collector of T1 should be just low enough to prevent the following transistor (T2) from conducting. This voltage can be adjusted within certain limits using P1. As soon as an object comes between D1 and T1, the light shining on T1 will be partially or fully blocked, causing the IR transistor to conduct less current. As a result, the voltage on its collector will increase, producing a brief rise in the voltage on the base of T2. This will cause T2 to conduct and generate a negative edge at IC1. This negative edge will trigger the monostable multivibrator, which will then hold the output signal on pin 3 high` for a certain length of time (in this case, one second). At this point, two things will occur. First, a buzzer will be energized by the output of IC1 and produce a tone for approximately one second. When the buzzer stops, a negative edge will be applied to the clock input of IC2, causing the counter in IC2 to be incremented by 1. IC2 is conveniently equipped with an internal binary-to-BCD decoder, so its outputs only have to be buffered by IC3 and T3 to allow the state of the counter to be shown on the 7-segment display. Switch S1 can be used to reset the counter to zero. If a one-second interval does not suit your wishes, you can modify the values of R3 or C1 to adjust...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Frequency-to-volt age converter
    Low cost Ethernet shield with ENC28J60 using Arduino
    Eico667 troubleshooting
    12V Lamp flasher circuit
    The worlds smallest pong game
    PC computer based frequency meter circuit diagram
    Motion Detector with PIR Sensor
    Racal RA17C18
    Equipment in use
    On-Off Temperature Control
    Preamplifier For Soundcard
    AM Synchronous Demodulator



    Top