8 input NAND gates

Discussion in 'General Electronics Chat' started by Dominick, Dec 6, 2008.

  1. Dominick

    Thread Starter Member

    Dec 6, 2008
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    Hello everyone,
    first time to this site and forums and was hoping you could help my with something.
    I have been looking for an 8input NAND gate, looks like mouser sold them
    but have discontinued them any other places?

    If this is any help I technically need a 7 input but an 8 was close enough
    so I coupled one input to + to get my 7.
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    If you mean the SN7430 , that seems to be sold at Ralphs Electronics (if stock did not run out yet)

    Did you consider the CD4048 cmos ?
    See attached datasheet.

    Greetings,
    Bertus
     
  3. mik3

    Senior Member

    Feb 4, 2008
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    If you can't find a 8 input NAND gate you can take two 4 input NAND gates and wire their outputs into the inputs of a 2 inputs NAND gate to make a 8 input NAND gate.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    You need to specify a logic family before we can make good suggestions. Old 74xx TTL isn't compatible with anything but 74LSxx. 4000 CMOS and 74HCTxx are lots more available.
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    That doesn't make an 8 input NAND. If you take two 4 input NAND gates and wire their outputs into the inputs of a 2 input NOR gate, and follow that with an inverter, which can be made from another NOR gate, you will have an 8-input NAND.
     
  6. Dominick

    Thread Starter Member

    Dec 6, 2008
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    WoW apparently I am out of touch with electronics these days. :(
    Are there any cross reference books out there?
    Worst thing about it is im using an old version of electronics workbench
    because I can afford anything else lol.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    You could use a CMOS 4073 or a TTL 74x11, which are both triple 3-input AND gates.

    Run the outputs of two of the gates to two of the inputs of the 3rd gate.

    This leaves you with a 7-input AND gate. Then run the output through an inverter.
     
    Last edited: Dec 6, 2008
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Here are two pages of the wikipedia that will give an overview:
    1) the old 74XXX TTL serie
    http://en.wikipedia.org/wiki/List_of_7400_series_integrated_circuits
    2) the newer 4XXX cmos serie
    http://en.wikipedia.org/wiki/List_of_4000_series_integrated_circuits

    Here are also some links on digital electronics of the EDUCYPEDIA:
    http://www.educypedia.be/electronics/digital.htm

    There are more pages like that over there:
    Digital electronics:
    Arithmetic circuits D/A-A/D converters Number systems Codes and decoders Flip flops Technology Counters and registers General overview Technology-CMOS Digital logic Memories Technology-TTL Timers and oscillators


    Greetings,
    Bertus
     
  9. Dominick

    Thread Starter Member

    Dec 6, 2008
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    Thanks bertus most appreciated, I have not built any projects since I got out of school back in 1999.
    Now that I want to start my HO scale model railroad back up I will be getting back into building all my own electronics for it.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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  11. Dominick

    Thread Starter Member

    Dec 6, 2008
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    Thanks that is the one I have booked marked :D .
    I built this one in electronics workbench
    http://home.cogeco.ca/~rpaisley4/20stepTraffic.GIF

    but the outputs that are linked would not work as drawn
    soo thus the resin for the 8 input NAND gate but now that I think of it
    I might be able to do the same with 2 4017s and a lot less other ICs
     
  12. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The drawing with the 74145's is correct.
    The outputs are open collector outputs.
    The outputs may be connected.
    See the picture on the site :

    [​IMG]

    Greetings,
    Bertus
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    The 4017 would only work if you had open-collector transistors (or open-drain MOSFETs) on each output. You can't simply wire the outputs together as you can with the 74x145; as the latter DOES have open-collector outputs.

    You could use a ULN2803 or ULN2804 (depending upon your logic voltage) as a driver IC; both contain eight Darlington pairs; the main difference between them is the input base resistance. The 2804 is for 6-15v CMOS logic.

    You might be interested in a slightly different approach; a 4017 timer where the duration of each output (0-9) can be set separately. See the attached for the basic idea.

    In your case, you'd use Q0 as a normal timer (like the others). This circuit originally came about due to someone wanting a timer that had variable times between output pulses. It would be very easy to adapt this to traffic light controls.

    4093 quad NAND gates (with the inputs for each gate tied together) could be used instead of the 40106 inverters, but you would only get 4 gates per IC instead of six inverters.
     
    Last edited: Dec 6, 2008
  14. Dominick

    Thread Starter Member

    Dec 6, 2008
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    bertus I knew you can connect them together but electronics workbench did not like that would not do a simulation right.
    and as of right now I can't seem to get circuit maker 2000 to do a simple
    sim. keeps giving me an error even on a simple 555 timer.
     
  15. bertus

    Administrator

    Apr 5, 2008
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  16. Dominick

    Thread Starter Member

    Dec 6, 2008
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    Thanks I was just trying to get some thing running before I bought
    any components because the circuit I'm making is alot larger than just the traffic lights.
     
  17. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    For large input circuits I tend to use diode gates. Diodes can actually take less board space than chips, and bridge gaps better.
     
  18. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Ohhhh yes. Thanks for the correction, I got confused with AND gates.
     
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