| The Power of Lights | 24 Jun 2007 at 06:52AM |
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The Power of Lights A Basic Guide For Troubleshooting Your Electrical Lighting By Rich Knapfel Drawings by Rich Knapfel (Please e-mail me if you would like the drawings) What makes a dollhouse a home? Well, many features add to the value and realism of a miniature project. However, nothing adds more realism to a piece than the warmth of lights. Lights have a special way of accenting a wall painting or illuminating the path down a long hall. In any case, lights compliment a project in a way that no other accessory can! However, what happens when the lights go out and we are forced to view our miniature mansion in total darkness. If you encounter problems with your miniature electrical circuits, fear not, because you can fix these issues without an engineering degree. To do this we must discuss some of the simplest rules of electrical theory. The diagram in Figure 1 is a simple circuit, which may be found in a dollhouse or room box. Let’s discuss each component of the circuit.
First, there is a power source. In this case, our power source is 12 volts. This 12 volt source can either be 12 volts alternating current (AC) or direct current (DC). It is important to note that current flows, not voltage. Voltage induces current flow in the same way that gravity causes water to flow down hill. In our simple circuit, current flows from the negative side of the source to the positive side. The negative side is represented by the short line and the positive by the long line of the schematic symbol. The load for our circuit is in the form of a lamp. The lamp is identified by the schematic symbol and the label L1. When the circuit is activated, current flow is induced by the 12 volt potential. The flow of current must travel to our load and finally illuminate the light bulb. Electrical circuits typically have a way of switching the current flow on and off. In our circuit, switch S-1 is the way we control current to our lamp. When S-1 is closed (turned on) current starts to flow from the source and we light our miniature room. (See the circuit in Figure 2)
Troubleshooting Your Project - So, what could cause the light not to work? Well, there are a few reasons for the dark room. The following table lists some of the possibilities.
Test Methods & Practices - When testing your electrical wiring, it is easy to determine the presence of an open circuit. If you troubleshoot your wiring with a Volt/Ohm meter, you will find that the source voltage will be present across an open circuit. Let’s take a look at this a little closer. If you inserted a volt meter across the area that the "open" arrow is showing in Figure 6, you will read the applied voltage. In this case, 12 volts is present at the open trace in your miniature light circuit.
Now, suppose there is a staple or metal object shorting the two electrical lines from you source. The symptom, in this case, would be no current flow to lamp L1. When there is no current flow, the lamp will not light. The current has taken the "path of least resistance" around lamp L-1. The lamp component offers more resistance than the short across the circuit. To troubleshoot this circuit, lift one of the leads of bulb L-1 or completely remove the bulb. Under normal conditions you should read 12 volts across the open circuit. If there is a short across the circuit (represented by the green line) you will read 0 volts on your meter (see Figure 7).
Conclusion - We all want our lights to shine forever; however, if your project turns to the dark side, you will have the necessary knowledge to repair any electrical faults that may come your way. |