As shown earlier, MTH uses a single 47uF, 35V capacitor for the 2 red marker LEDs in a passenger car. As you add more LEDs (such as converting the interior bulbs to LEDs), more capacitance is needed as there is more current drawn during the dropouts. Everyone's situation is a bit different wrt how clean you keep your track, tolerance for flicker in the first place, number of turnouts, etc., but I'd say the typical values that the guys use when there are a bunch of LEDs would be 220 uF, 35V (or 50V).
The inductor used for DCS in passenger cars is 22 uH, 1/2 Watt.
Now in class they talk about energy storage in an inductor and capacitor. But in this case the inductor is used for its complex-impedance to block hi-frequency signals, not for its energy storage. Your textbook tells you the stored energy (in Joules) for an L (in Henries) or C (in Farads) is 1/2 * L * I^2 and 1/2 * C * V^2 respectively. Seems about the same right? Well, let's look at some real-world numbers for a subway car. Let's say the current flowing to drive the LEDs is 50 mA total. And the voltage available to charge the cap is 18V. A 22 uH inductor with 50 mA flowing stores only 27 nanoJoules of energy. A 220uF cap charged to 18V stores 35 milliJoules of energy. The cap stores 1 million times more energy.
Sorry Stan but I got a question, You said before that when you put in the diode to the middle rail, It will reduce the voltage by half, are you sure this is correct? Ive read about voltage drop but i haven't read a topic that says a Diode will reduce the voltage by half
