Q:

Using a capacitor to smooth momentary voltage cuts

I'm building a model of a trolleytruck (very similar to a trolleybus). The steering system works with a servo but, because the overhead wires are not perfect and there are short voltage cuts, the servo moves randomly. I'm thinking of connecting a capacitor to smooth the voltage but I can't find any information on Google (everything that I can find is about rectifier circuits). So my questions are: Can I directly connect a capacitor between the servo power wires to smooth the voltage? If that's possible, how can I calculate the capacitance that it should have?
Thanks in advance and sorry for my bad English.

A:

Yes you can.
Depending on the current and break time the capacitor MAY need to be large.
Voltage drop is ~=
V= T x I / C (Volts seconds Amps capacitance).You can rearrange that as
C = T x I /V or other. 
eg for a 0.1V drop for a 50 ms break at 100 mA  .
C = T x I / V
= 0.05 x 0.1 / 0.1 = 0.05 Farad = 50,000 uF  (!)
Change the values to suit. 

