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Competition #1: High/Low Pulse Indicator

Discussion in 'Entries' started by ElectroMaster, Jul 3, 2008.

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Poll closed Aug 17, 2008.
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  1. ElectroMaster

    ElectroMaster Administrator

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    ***** To vote for this project please answer the poll above. *****


    Project: [FONT=Verdana,Verdana][FONT=Verdana,Verdana]High/Low Pulse Indicator[/FONT][/FONT]

    The purpose of this circuit is to indicate the status of a present pulse.
    When a high pulse present it will display the letter "H" & when a low pulse present it will display the letter” L” in the seven segment.

    Parts List

    2N 2222 NPN Transistor 1
    1N 4148 Diodes 8
    1K Resister 1
    470R Resister 1
    Common Cathode SSD 1

    Circuit Diagram

    [​IMG]

    Operation

    When there is low pulse, there’s no any current flow through collector & emitter, so the first three diodes will forward biased & the other five diodes won’t get any current from the input, this allows current flow to d, e, and f segments via the first three diodes. Then it will display the letter “L” on the SSD.

    When there is high pulse, current starts flow through collector & emitter. So the first three diodes will not get any current & the same time the other five diodes will get current through input so they starts to forward biased & pass current to the b, c, e, f, g segments. This allows to display the letter “H” on the SSD.

    Note that the diodes going to e & f segments are combined together because those segments are common to both letters.

    Construction

    Construction is simple, it may take few minutes to assemble in a vero or in a breadboard. The circuit needs a 5V supply. The display brightness will vary if you change the value of R1.


    ***** To vote for this project please answer the poll above. *****
     
    Last edited: Jul 3, 2008

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