[sdiy] an XOR question

[Theo]

For any 3 or 4 input logic function just use a multiplexer IC.
A 74xx150 is a 16 to 1 selector/mpx usable for 4 inputs, if 3 inputs are needed there are smaller 8 to 1 ICs eg 4051, 74151.
The select lines are your logic inputs and Q is your logic out put, the data inputs connect to 1 or 0 depending on your tables of truth.

HTH
Theo

  ----- Original Message ----- 
  From: Schierl, Dan 
  To: synth-diy at dropmix.xs4all.nl 
  Sent: Sunday, September 12, 2004 12:22 AM
  Subject: [sdiy] an XOR question


  Hi list--
  I have an application I'm working on in which I need to perform an exclusive OR on 4 inputs. Since I don't think anyone makes a 4-input XOR, I tried to rig something up using some CMOS chips. My first attempt was a little too simplistic (i.e. wrong), which I didn't realize until I'd already wired it into my application. I think my second attempt works (haven't tried it yet, tho) but i think it might be overkill. 

  Go here: http://people.msoe.edu/~schierld/temp/xor.html to see my two ideas.

  My question is: the second idea is pretty much a literal definition of an XOR gate, but I wonder if there are any trick ways to make one of these with fewer chips. Any thoughts you might have would be appreciated. thanks!
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