Author 
Patching an XOR Gate? 
hinterlands303 
I've figured out how to patch or, and, nor, and nand gates with a combination of mixers, vcas, inverters, and offsets, but are there any good ways to patch up an xor gate without a dedicated logic module?
Would this work?
Gate A into mixer channel 1
Gate B into inverter into mixer channel 2
Mixer out to rectifier.
Rectifier out = XOR gate 

cptnal 
Is this an academic exercise or do you have a pathological dislike of logic modules? 

mojopin 

hinterlands303 
Thanks! The search function in the forum isn't working for me but I should have just done a google site search. 

hinterlands303 
cptnal wrote:  Is this an academic exercise or do you have a pathological dislike of logic modules? 
Part of it is just trying to get my brain around it, and the other part is deciding if I really need my rarely used logic module if I can approximate the functions other ways. 

cptnal 
hinterlands303 wrote:  cptnal wrote:  Is this an academic exercise or do you have a pathological dislike of logic modules? 
Part of it is just trying to get my brain around it, and the other part is deciding if I really need my rarely used logic module if I can approximate the functions other ways. 
Interested because I just bought a Doepfer and I'm wondering, "what else can I do with this other than the obvious?" I'll be watching this thread for any of those gems that pop up in unexpected places. 

mskala 
If your logic levels are positive and negative (instead of positive and zero), then any fourquadrant multiplier or "ring modulator" that works at DC will do the XNOR function. Add negative offsets on input to convert positive/zero logic levels to positive/negative; invert one input or output to make it XOR instead of XNOR; and use a comparator on output to convert back to positive/zero logic if you like. 

cornutt 
Another way of getting an XOR, if you have two signals at logic levels:
1. Electrically invert one of them, e.g., if it's +5V, it becomes 5V.
2. Add them. A simple passive adder (two resistors) will do.
3. Run the output of that through a fullwave rectifier. 

hinterlands303 
cornutt wrote:  Another way of getting an XOR, if you have two signals at logic levels:
1. Electrically invert one of them, e.g., if it's +5V, it becomes 5V.
2. Add them. A simple passive adder (two resistors) will do.
3. Run the output of that through a fullwave rectifier. 
This is a much more elegant way of noting the patch I had in my first post much easier to follow. I tried it and it works great. Plus if you're a in Euro the WMD/SSF Toolbox has all of these functions so it's super easy to patch up. 

frijitz 
