Hi, I'm trying to understand the operation of the schematic I attach. http://imageshack.us/photo/my-images/853/abampschematic.png/ What's the point of having the input at the Q1 collector? I can understand the more common structure shown in wikipedia ( http://en.wikipedia.org/wiki/Push–pull_output ) but I have trouble with the first one. Can anyone explain me how it works? Thanks.