Building comparator from discrete components?

[mishima]

Hi, I'm interested in building a breadboard version of the simplest comparator using transistors and resistors. Ultimately I'd like to understand the LM393 but looking at the datasheet schematic, it seems quite complicated. I was hoping there was a simpler comparator I could mimic to start out with. Thanks.

 

[mishima]

Like how about this for the 139, it seems more doable/understandable for my skill level:

Is there something even simpler? Or is anything in this circuit not necessary for understanding the comparator action?

 

[NascentOxygen]

A comparator is based on a differential amplifier. See Q10 and Q13. http://www.allaboutcircuits.com/worksheets/diffamp.html

 

[mishima]

Thanks, that's just what I needed!