DAC for Stamp

Comments

• Martin Hebel Posts: 1,239

  2005-11-17 05:43 edited 2005-11-17 05:43

  Instead of a DAC, here's something to consider.
  The attached image is adapted from the upcoming Process Control text (to replace Industrial Control).
  By PWMing P2 you can control the output of the op-amp buffer from about 0.5V to 5V, and the RC filter only needs to be refreshed every couple seconds.
  
  The RC filter will give an average voltage of the PWM value, which will be buffered by the op-amp (LM358) for driving a small load. It has an 8-bit resolution based on the PWM instruction
  
  PWM 2, 128, 100 'output would be approx 2.5V.
  
  Sorry, haven't figured out how to insert images yet....
  
  -Martin
  
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  Martin Hebel
  
  Electronic Systems Technologies
  Southern Illinois University Carbondale
  Personal Links - ·Lot of BASIC Stamp info
  and
  SelmaWare Solutions
  StampPlot Pro Version 3 Release 4
  Graphical Data Acquisition for your Micro and Imagination!
  Now allows additional controls to be added, or developed.

  

  

  RC_Filter_w_buffer.JPG

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• PJAllen Banned Posts: 5,065

  2005-11-17 20:59 edited 2005-11-17 20:59

  Try a DAC0806 or DAC0804.· They're 8-bit jobs, but for a voltage out you'll need to add the current-to-voltage amp (the complete circuit is in the datasheet/s.)
  
  www.jameco.com/wcsstore/Jameco/Products/ProdDS/14912.pdf
  
  Jameco has DAC0808 (MC1408) for less than $2.
  
  They're not the last word in DAC'ing, too slow to do Hi-Fi audio or anything, but they're easy to work with, and understand, and not uber-finicky like.