Design

80 Hacking Electronics

On the face of it, you can think of capacitors as being a bit like batteries. Both store charge. However, there are some very important differences.

● Capacitors only store a tiny fraction of the charge that a battery of the same size can store. ● Batteries use a chemical reaction to store electrical energy. This means their voltage remains relatively constant until they are spent, at which time it falls off rapidly. Capacitors, however, drop evenly in voltage as they discharge, just like the level of water decreasing in a tank.

Design

Figure 4-33 shows the schematic diagram for this modification.

The headlights (D2 and D3) are powered all the time from the slot car’s connection to the track, so whenever the motor is running the LEDs will light.

The brake lights are more interesting. These will automatically come on when the car stops, and then go off after a few seconds. To do this, we make use of a capacitor C1.

Figure 4-33 A schematic diagram for the slot car modification