Skip to main content
Engineering LibreTexts

5.3: Implementing the Circuit

  • Page ID
    26976
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    The two expressions given previously will now be implemented in a breadboard circuit to confirm that they are indeed associative. This exercise also serves to show how to implement circuits which require cascading of outputs from one gate to another in a circuit, and to better see how the circuit diagrams from Logisim can be translated into circuits implementations.

    \(\PageIndex{1}\) Implementing the serial AND circuit

    The serial AND circuit from Figure 5.2.1 is implemented in Figure \(\PageIndex{2}\) below. Step by step instructions for implementing this circuit follow, and the numbers correspond to numbers in the picture of the circuit in Figure \(\PageIndex{2}\). You should start with a circuit with the powered 7408 chip on the breadboard from Chapter 3 (pins 7 and 14 connected to ground and positive respectfully). The pin layout schematic from Figure 4.5.3 is repeated here as Figure \(\PageIndex{1}\) for ease of reference in the steps below.

    1. This circuit requires 4 inputs, labeled A, B, C, and D. Install 4 switches just as in Chapter 3, and as shown in Figure \(\PageIndex{2}\).
    2. Install and power the 7408 chip (quad AND gate).
    3. The first two switches, A and B, form the inputs to the first AND gate (pins 1 and 2).

      The output is on pin 3 is the result of A*B.

    4. The output from the first AND gate (pin 3) is the input to the third AND gate (pins 13).

      This is done by connecting pin 3 to pin 13.

    5. Connect the switch C to the second input to the third AND gate (pin 12). The output from this AND gate, on pin 11, is ((A*B)*C).
    6. Connect the output from the third AND gate, pin 11, to the fourth AND gate by connecting pin 11 to pin 10. Note that in the picture this connection is a bare wire, and might be hard to see.
    7. Connect the second input to the fourth AND gate by connecting switch D to pin 9. The output of the third AND gate, pin 8, is (((A*B)*C)*D).
    8. The final output of the circuit is the output of the fourth AND gate on pin 8. Connect pin 8 to the led. When all 4 switches are turned on, the LED should light.
    Figure \(\PageIndex{1}\): 7408 pin configuration diagram

    Screen Shot 2020-06-26 at 6.21.03 PM.png

    When this is completed, your circuit should light the LED only when all 4 switches are in the on position.

    Figure \(\PageIndex{2}\): Serial AND implementation

    Screen Shot 2020-06-26 at 6.22.18 PM.png

    \(\PageIndex{2}\) Implementing the parallel AND circuit

    The parallel AND circuit shown in Figure 5.2.2 is implemented in Figure \(\PageIndex{3}\). This circuit is created from the serial circuit in Figure \(\PageIndex{2}\) by making the following modifications.

    1. Move switch D so that it is now input to the second AND gate, pin 13.
    2. Move the output from the first AND gate so that it is now input to third AND gate, pin 9.

    This circuit should produce the exact same output as the circuit in section \(\PageIndex{1}\), e.g. the LED should turn on when all of the switches are turned on.

    Figure \(\PageIndex{3}\): Parallel AND implementation

    Screen Shot 2020-06-26 at 6.24.45 PM.png


    This page titled 5.3: Implementing the Circuit is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Charles W. Kann III via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

    • Was this article helpful?