Can someone please help with my homework? I can't seem to find a decent schematic diagram for a 5V DC Tripler.

 

3 5 volt batteries in series?

 

You need to show YOUR best effort to solve YOUR homework. We can then use that as a starting point to help guide you from where you are to where you are trying to go. But don't expect someone to just do your work for you.

 

Maybe this link would help you :

http://www.electronics-tutorials.ws/blog/voltage-multiplier-circuit.html
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/voltage-multipliers/