recommendation needed for ADC

Discussion in 'General Electronics Chat' started by hunterage2000, Dec 30, 2012.

  1. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    Hello all,

    Can anyone recommend an ADC that takes an input voltage from a thermistor bridge circuit between 0-5VDC and outputs 8 parallel digital signals?

    I dont know how to use a Microcontroller so Im going to use a 7seg display.
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
  3. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    I was going to use a range of 0-50C with 6 bits, 51 outputs used and 11 spare

    I was thinking split the 6 bits so 3 bits represent a decimal number and using 2 BCD to 7seg.
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    When you split a 6 bits binary value into 2 3 bits binary values, the BCD decoders will show values of 0 to 7 each.
    This will not give the wanted values of 0 - 50 on the dual display.

    Bertus
     
  5. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    maybe use 8 bit and split to 4 each, How would this usually be done without a MP?
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You can take the 6 bits and convert the values to BCD using an 74185.
    See the attached data sheet for more info.

    Bertus
     
  7. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    yeah great, do you know of a simple ADC for this kind of application? The analog input to it is DC between 0 - 5V.
     
  8. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Have a look at the ADC0804.
    You can feed the 6 highest bits to the 74185 and the next lower bit set a 0 or 5 for the half degrees.

    Bertus
     
  9. MrChips

    Moderator

    Oct 2, 2009
    12,440
    3,360
    A simpler solution is to use ICL7107 ADC.
     
  10. crutschow

    Expert

    Mar 14, 2008
    13,002
    3,232
    I'm with MrChips' recommendation. That device will directly drive an LED or LCD display (depending upon the model) and gives you nearly 11 bits of resolution (3 1/2 digits or 1999 decimal full scale).
     
  11. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    400
    0
    Ideally a 5 bit ADC is what I want so I can have a range of 0 - 31C. I have setup a working 8 bit Adc0804 in Proteus. Can this be modified to 5 bit?

    I'll also look into the ICL7107 ADC.
     
  12. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    You can take the 5 highest bits of the ADC0804.
    Then the bits will change over the 0 - 5 Volts range.

    Bertus
     
Loading...