if i build a basic VCO, and i want to plug others into it or go out of it, i assume i follow the logic on the pins, right? (output pin for out...). what about input? would that be v+?
I don't really understand what you're asking. If you want to combine the output of a couple of oscillators, you'll need some sort of simple mixer.
Have a look at some existing modular synthesizer designs, and see how they do it.
judging the data sheets, lets say of a 555 timer, pin 3 is output , pin 8 is voltage in, etc...can i follow this logic in going modular? would the output jack be connected to output pin 3? that is just the example of a 555...am i close?