Capacitor Installation

Figure 4 - Direct Switch Activated Device:

Figure 5 - Relay Activated Device:

FILTERING NOISE
Noise can often be filtered out of a circuit with the use of a capacitor. Since noise approximates an Alternating Current (AC) signal, it sees the capacitor as a resistor. The Direct Current (DC) signal used to power the vehicle's systems will see the capacitor as an open circuit.

CAPACITOR SIZING
In this manner and with the proper selection of capacitor size, noise can be separated from the desired signal. The effective capacitance can be changed by adding capacitors in parallel and in series. When installing a capacitor in a circuit, start with one 0.47 micro-Farad capacitor from the power circuit to ground (see accompanying images). If this does not yield the desired results, add in a second capacitor of equal value in parallel. If this still does not eliminate all of the noise, try adding a third capacitor in series with the first. Refer to the accompanying images for an illustration of these three connections. Any further addition of capacitors to this circuit is not likely to increase the amount of noise filtered out.