Tech 167...

Discussion in 'The Projects Forum' started by Rajit28, Oct 29, 2008.

  1. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    How do we make a R2R ladder network wor?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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  4. bertus

    Administrator

    Apr 5, 2008
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  5. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    everyone's advice was very helpful.:):cool:
     
  6. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    is 7493 a 4 or 8 bit DAC.

    i need a 4 bit DAC?
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
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    The 7493 is a counter, not a DAC.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Just adding to Thingmaker's comment,
    The 7493 is a 4-bit binary up-counter.
    If you're going to use an R2R ladder on the outputs to create a ramp generator, I suggest that you use the 74HC93.
    Whether the ramp slopes up or slopes down depends upon how you connect the R2R ladder to the outputs of the '93 counter.

    See the attached for a similar idea.

    The LF351 is used as a buffer amplifier. It was really not a good choice for this application, because the inputs and outputs are not rail to rail, but it works OK for the first 14 of the 16 discrete steps. Since CMOS logic has very limited output current, the R2R values need to be rather high; so a buffer amplifier is necessary for all but very high impedance outputs.

    The LM339 provides a means to terminate the ramp early, by resetting the counter.
    The 4020 is a CMOS dual binary up-counter.
     
    Last edited: Nov 3, 2008
  9. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    any recommendations for buffer amplifiers welcome.
     
  10. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    any one know where to find buffer amplifiers.:confused:
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
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    Would any of the following suffice?

    TLCV2772

    TLC2774

    DN230

    LT1635

    LT1677
     
  12. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    :cool: thanks for everyone'shelp this thread can be closed.
     
  13. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    The LF351 is this a good buffer amplifier?
     
  14. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    do you know the website for buffer amplifiers?:)
     
  15. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    Best place to find clocks for 7493 IC chips.

    the clock measures pulse length in micro seconds i think

    not sure.:)
     
  16. beenthere

    Retired Moderator

    Apr 20, 2004
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    Do you need a clock source? You can find clock oscillators with logic outputs in 4 pin IC packages. A 1 MHz oscillator will give microsecond timing.
     
  17. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    thanks..:D
     
  18. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    do you know where to get 4 pin IC packages. in my college we normally

    use 16 pins or 8 pins or something 4 pins looks a little small

    don't you think?:confused:
     
  19. Rajit28

    Thread Starter Active Member

    Oct 21, 2008
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    :cool:
    4 pins was good. thanks to help of forum

    my project was successful.:cool:
     
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