8 transistors or 2 16 pin dips

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Discussion in 'General Electronics Chat' started by Robin Mitchell, Dec 26, 2009.

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  1. Dec 26, 2009 #1
    Robin Mitchell

    Thread Starter Distinguished Member

    Oct 25, 2009
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    Hi guys

    i need to make a desicion (spelling?).
    The 4044 is very hard for me to get since rapid online, the cheapest place only sells them in bulk. Now, the 4044 is very important since i use it as an eletronic switch that can drive data to a bus since it is tristated. Now, i know i could do the job even more cheap with transistors, but they take alot of room.

    I have seen bilateral switches like the http://www.rapidonline.com/netalogue/specs/83-0338.pdf
    is the control like a base of a transistor so i put a high on the control and then the signals can travel through?​
    ​
    ​
    ​

    ​
    Which one should i use, the 44's or transistors?
    Also, are there any chips that are like DIP with eletronic switches?
    (PS, i have had a look at some 8 bit bus drivers, very complicated though :( )
     
    Last edited: Dec 26, 2009
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  2. Dec 26, 2009 #2
    Wendy

    Moderator

    Mar 24, 2008
    21,367
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    I think you are suffering from target fixation. RAM is common in many forms, it is possible that someone in the UK knows a different (cheap) solution.

    I had an Altair 6800 a while back, nothing but toggle switches and LEDs, complete with manuals. It was going to waste in my garage, so I gave it to a friend. It only had 1Kbyte of RAM (8 bit words). If you need to start smaller (and keep looking) it will allow you to experiment.
     
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  3. Dec 26, 2009 #3
    Robin Mitchell

    Thread Starter Distinguished Member

    Oct 25, 2009
    874
    295
    What?

    Bill, I love you because your funny, all knowing and a fantastic friend, but im getting annoyed with your riddles and answers that lead to more questions. I just want to know weather to use transistors, 44's or them weird switches because i like the look of the switchs

    again i apologise for sounding rude but im a little....on the edge (not drugs :D)
     
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  4. Dec 26, 2009 #4
    bertus

    Administrator

    Apr 5, 2008
    18,596
    3,605
    Hello,

    Do you have a schematic on how you plan to use the transistors or chip?
    There are tri-state busdrivers like the 74125.

    Greetings,
    Bertus
     
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  5. Dec 26, 2009 #5
    Wendy

    Moderator

    Mar 24, 2008
    21,367
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    Me, all knowing? A joke in itself. I've just lived a while.

    My point is look for something smaller to hold you over.

    My advice relates to my tag. I'm guessing you want to power this sucker up, and start moving bytes around. You don't need 256K to do that, though that can still be an end goal.

    I don't get parts free. It isn't something I've ever done, though I wish you luck in doing so. I understand why you want tristate logic, it was invented for computers.

    That just gave me a thought though. You can buy tristate buffers. This would let you use whatever you have in the way of memory and still interface to your circuit the way you've obviously conceived of doing. They were cheap (Radio Shack was dumping them a couple of years ago). I think the number was a 74244. It came in CMOS form too.
     
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  6. Dec 26, 2009 #6
    Robin Mitchell

    Thread Starter Distinguished Member

    Oct 25, 2009
    874
    295
    Bill, this matter is completly diffrent to the other thing, with the FRAM chips.
    But these chips look good so thanks :)
    Here I just need an efficiant way of selecting data being driven to a common bus
     
    Last edited: Dec 26, 2009
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  7. Dec 26, 2009 #7
    MaxSmoke

    Active Member

    Oct 29, 2009
    35
    0
    Have you not considered an octal tristate buffer, something like the 74LS245 is bi-directional. If you are looking for something with CMOS levels then the 74HC245, both parts work with +5V logic. For a faster part at +3V3 supply and surface mount option, then the 74AC245. If you need unidirectional buffers, then the 74xx244 would be an option.

    As Bill suggested earlier, look at what other devices are available other than the 4044 ;)
    An analogue switch could be used, but they are not normally as fast. Take a look at these links below:

    74HC244
    74HC245

    These parts are available from Farnell in the UK, they do take orders by 'phone. The pdf specifications are on the Farnell website.
     
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