Question

What do the following circuits do?
http://i.imgur.com/Fj1E1CU.jpg?1

Answer 1

hint:
the circuit at the right side, can be drawn as below:

Answer 2

it is the equivalent circuit

Answer 3

now, if the voltage at point A, is less than \(2 \cdot 0.6\) volts, then current flows through \(R_{load}\) only
whereas, if voltage at point A, is Greater than \(2 \cdot 0.6 \) volts, then current flows through the diodes D1 and D2, since the sum of their internal resistances is less thjan the value of \(R_{load} \)