DC Blockers:
Resistors are inserted into the circuit to prevent large current, protecting the circuit.
Capacitors prevents the flowing of DC, and allows AC. This protect the signal output
Non-inverting amplifiers:
to have a gain of two, meaning 1+r2/r1=2, r2 is equal to r1.
when gain is one it means r2 is 0. when gain is 2 r2 is equal to 1.
The amplified wave is at different position than the original, might because it is negative.
Tiankai Li 