Could anyone post a circuit to build rope climbing ROBOT?

What's the difference between a voltage and current source... What is the need for a current source when voltage source itself produce current:sshhh:

What is the need for considering effective capacitance/resistance/inductance? In what way does it help building the circuits.. Why do we calculate it?

Why is that in a circuit made of series connection of capacitors the total capacitance of capacitors in series is equal to the reciprocal of the sum of the reciprocals...

Thank u guys.. i'm enlightened

Can anyone help me out in explaining why transformers are considered as passive circuits. Transformers performs by stepping up/down voltage/current,changes low input power to high output and vice versa.But these...