TTL 101..Digital Inverters

Discussion in 'FAQs' started by kf4jqd, May 16, 2005.

  1. kf4jqd

    kf4jqd Active Member

    Jan 14, 2001
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    Hi Gaugers:

    I just want to say, I don't know how long I can talk about TTL. Because we are moving very soon. What is TTL, you ask? It stands for Tansitor-Transitor-Logic. TTL electronics are the very basic building block for computers. The work like a basic switch. The benifit, they use very little power.

    There are many kinds of TTL's, NAND, AND, OR, NOT, and inverter gates. The input(s) and output(s) are based on highs (1) and lows(0). What does the high mean? It means the TTL is on. The low means the TTL is off. Just like your switch that turns our layout on and off.

    Ok now the inverter:
    The number for the basic inverter chip is 7404. There are varies types of inverters. There is only one input and output of an inverter. First I must say they work on a 5vdc power source. When you add a high to the input. The output will go low. If you add a low to the input. The output will go high.

    Here is the logic diagram:
    Input is H = Output is L
    Input is L = Output is H

    Now you are asking. What can I do with this? Suppose you have a green signal for your train at the station. But down the same line you want it red. Instand of using a relay. You can "invert" the signal and make the light red! You must use LED's for this to work.

    This is very easy to put together. All you need is 5vdc a filter capasitor. There are more than one invertor per chip. They are very cheap.

    Andy :wave:

    Attached Files:

  2. Matthyro

    Matthyro Will always be re-membered

    Dec 28, 2000
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    Thats a neat method Andy. Thanks