Can you have a logic circuit with 3 outputs?

I have an assignment to do and the question is regarding building a logic circuit for an industrial oven.

There will be three input points labelled A B and C to a control circuit. It states that logic 1 must indicate the temperature is correct.

Three LEDs will be used to indicate the conditions of the circuit, with only one LED on at a time.

Red - if the temperature is correct at 1 point or at no points

Yellow - if the temperature is correct at 2 points but incorrect at any one point

Green - if the temperature is correct at all three points.

Is this all one circuit, and three outputs or have I misunderstood the requirements for this question? If it's one circuit how do I make it so only one LED is on at any one time?

If anyone could help that would be massively appreciated - I've been sat down for hours and I just can't understand what to do.

3 Answers

  • John
    Lv 6
    1 month ago

    I would use an Western Electric, telephone stepper switch. Cost prohibitive and heat sensitive. LOL. A simple logic circuit, Boolean Algebra. 

  • 1 month ago

    Three inputs, each goes to three circuits.

    Circuit #1 controls the red LED.

    Circuit #2 controls the yellow LED.

    Circuit #3 controls the green LED.

    Now you just have to design each circuit. That's 3 different designs.

    Using a 3-8 decoder is a good idea, but I bet you're supposed to use just basic gates: AND, OR, NOT, NAND, NOR.

  • 1 month ago

    as I understand it, there are 3 outputs each driving a LED.

    you have inputs A,B,C

    red if A,B,C are all 0 or if one of A,B,C = 1

    Yellow if any 2 of A,B,C =1, the other =0

    green if A,B,C all = 1

    I'd use a 3-8 decoder which gives you outputs of 0 thru 7

    A B C  output

    0 0 0   A

    0 0 1   A

    0 1 0   A

    0 1 1   B

    1 0 0   A

    1 0 1   B

    1 1 0   B

    1 0 1   B

    1 1 1   C

    so you take outputs 0,1,2,4 to a 4 input OR gate for red

    outputs 3,5,6 to a 3 input OR gate for yellow

    output 7 for red.

    An ALS138 for the decoder, and a bunch of gates following it for the OR gates, and some LED drivers.

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