Gate symbols v real curcuits

Discussion in 'General Electronics Chat' started by DBoon, Jul 6, 2012.

  1. DBoon

    Thread Starter New Member

    Jul 3, 2012
    Hi, I'm hoping someone can help me by explaining what the + and - at the top and bottem of gates are. There are A and B inputs on the left and a C output on the right. So what are the + and - for?
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    I'd guess they are for power and ground, but if you showed what you were looking at I wouldn't need to guess.
    DBoon likes this.
  3. wmodavis

    Well-Known Member

    Oct 23, 2010
    They are active devices and require power to operate.
    + is where you connect the positive polarity of the DC power source and - is where you connect the negative side of the power source.

    You should get real familiar with the device specification sheet. The manufacturer produces those to help you understand how they work, how to connect them, what they do and many more important details. A real electronics buff sleeps with spec sheets.
    DBoon likes this.
  4. Wendy


    Mar 24, 2008
    Welcome to AAC!

    As a new member, some options are restricted and will require 10 posts from you to go away, such as editing old posts.

    You will note older member have their location posted in the upper right hand corner. This adds us in helping, as different parts of the world have access to different parts. You can update this in your profile.

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    Schematics and pictures are worth a thousand words. It is worth learning how to post drawing or images here when asking a question.

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  5. DBoon

    Thread Starter New Member

    Jul 3, 2012
    Thank you very much for your replies. It realy helps to know people care and will help new members to learn.
  6. takao21203

    Distinguished Member

    Apr 28, 2012
    It's off the thread topic but I would like to use this opportunity to ask for to make it mandatory to write some information about the location. It is ridiciuluos to come accross a rather bad post, maybe even bad english, and then don't even have a clue about location.

    People who can use complicate technology also should be able to know where they are based in terms of location.

    I am not saying anything about this post however.
  7. DBoon

    Thread Starter New Member

    Jul 3, 2012
    Anyway! My skimmatic is going to look very different to my actual circuit. But I want a NOT gate. Unfortunatly it is not listed in this list, found in another's post:
    4001 NOR gates
    4011 NAND gates
    4071 OR gates
    4081 AND gates
    4069 Hex inverters

    Could someone help me buy one or would it be best if I just made up my own gate by drawing some circuits, and buying transistors?
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    The Hex inverter is a NOT gate, just has a different name. The NOR and NAND can be made to work as a NOT gate and do more interesting stuff. You will quickly outgrow a NOT gate but you can literally build an entire computer just using NAND or NOR gates.

    As it happens, one of my first experiences with logic was building my own gates to supplement my small collection of IC's. This was ages ago when gates were built out of simple transistors (the RTL family).

    Building some of my own gates that way taught me a lot. The types you mention are all MOSFET types, and I don't think building them would teach you much, but it just might. Search out those types and see if you can get a data sheet with schematics, and see if it makes sense to you.
    DBoon likes this.
  9. crutschow


    Mar 14, 2008
    An Inverter is a NOT gate.

    Unless you really like soldering together a lot of parts, buying ICs to build a circuit is much easier. The CD4000 series of CMOS gates are relatively easy to use as long as you don't need to work much above a MHz switching frequency, and operate from a wide voltage range (read the data sheets before you use any ICs). You can buy them at virtually any of the electronic supply places such as Digi-key, Allied, Jameco, Mouser, etc.
    DBoon likes this.