perform automatic function

Discussion in 'The Projects Forum' started by karthiksrao, Oct 21, 2006.

  1. karthiksrao

    Thread Starter New Member

    Oct 21, 2006
    i'm completing my engg degree in mechanical field.. We were asked to do a project in mechatronics..

    The problem statement goes like this... the number of objects passing on a conveyer belt has to be sensed.. when the number has crossed a certain limit ... a signal has to be sent to the motor to stop the conveyor belt...

    I guess a led would do the trick for sensing the objects.. apart from that i have absolutely no clue , how to go about doing this..Please help me with the circuit to build this model...We've had a basic course in electonics. So i'll be able to understand the basic components in an electronic circuit...

    We've been given liberty to buy any standard unit that is available in the market.. also we've got to complete this in a week's time...

    thanks in advance.
  2. Papabravo


    Feb 24, 2006
    I see no reasonable chance of success in 1 weeks time.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    LED and sensor will work. Here is a divide-by-n counter:

    You should be able to breadboard this and get the bugs out in an hour or two.

    Making a marketable version would of course take more than a week, as Papabravo has opined.
  4. karthiksrao

    Thread Starter New Member

    Oct 21, 2006
    I'm not looking to build a marketable version.. its just a simple model..

    I have a few ideas.. I thought if we could use a phototransistor so that when light falls on the transistor from the LED, it will start conducting and voltage across it falls to 0 (logic 0) and when ther's no light falling on it.. voltage accross it will be Vcc ..(logic 1).. i thought of tapping these pulse voltages so as to feed it into a counter...can this be done??

    If it can be done , what are the components that will go into making the interface between the transistor and the counter?

    also.. I thought the counters are readily available in the market..Is it so.. ? or do we have to build the counter...
  5. BobJoe


    Oct 7, 2006
    2 8-bit ripple counters. have the input of one by a push button set up for the operator (call this C1) and a light sensitive resistor as input (must go through a NOT first) for the other ripple counter (C2). have each appropriate output connected by NAND gates. have a single wire connecting each NAND gate so as long as one has a value of logical 1 then your conveyor belt will turn. when C2 has counted up to the same logical value as preset my user on C1 all NAND gates will read logical 0. the output is then fed into a transistor which in turn switches off the conveyor belt.

    sorry i mostly came up with this on the fly and have no actual electrical experience so i dont know if this will work. also my appoligies if im not supposed to put logical in front of my 1's and 0's. the only problem that you may encounter is that the last object to go down the conveyor belt will just enter the the beam of the light for the resistor causing it to stop right there, you may want to tell it to count one extra to account for this.

    im curious though, will this work? or is there major flaw in it?
  6. thingmaker3

    Retired Moderator

    May 16, 2005
    Any old buffer would do.

    There are indeed monolithic divide-by-n counters available. Examples include the HCF4018B, the CD4059A, or the CD4018B. I don't know if one could be obtained quickly. The 74160 and 74161 should be readily available at many local supply houses.
  7. Søren

    Senior Member

    Sep 2, 2006

    Sure, you can buy a ready made counter module, looks just like a panel meter.

    If you haven't got any luck pointing the LED (might be a bitch to focus, since some light might creep "around" the goods to be counted), you could use a cheap LASER pointer instead - just use a power supply of a proper rating and block the button down.