The article describes how to wire tiny 12 volt flashlight bulbs into decorative string light for decorating houses during festivals like Diwali and Christmas.
What are String Lights
As the name suggests a string light is a wired lamp system in which many lamps such as bulbs or LEDs are joined together in series to form string or chain like arrangement. The series connections are specifically done to divide the supply voltage uniformly across the lamps and to ensure that this voltage value is within the specifications of the lamps.
Diwali and Christmas string lights are also popularly known as TORAN in India.
The articles describes in a very simple to understand language, the basic concept and also the entire wiring details of these TORAN lights or the string lights.
The article explains how tiny 12 volts flashlight bulbs can be strung up together by pieces of electrical wires by soldering them serially.
In one of my earlier articles I discussed and shared with you the moments and the celebration atmosphere of various Indian festive occasions. We also talked regarding the outrageous light shows generally accompanied with typical Indian festivals.
In the article we learned how to build a traditional illuminated STAR using bamboo canes and some colorful gelatin paper.
We also discussed about the very popular TORAN lights which are most extensively used during these festivals and I’m sure you all very share the making procedure of these TORAN lights here, which are also commonly known as string lights throughout the world.In this article we are going to discuss a very simple configuration of making AC mains operated string lights using ordinary small incandescent torch bulbs.Though the wiring may appear pretty straightforward, it too definitely involves some bit of calculations.
Before we study the complete connection details of the various designs covered here, grasping the basic concept would be handy.
A Simple Flashlight Wiring
A flashlight is the most simple and common form of electrical wiring that one can refer to. As shown in the diagram, the configuration includes a couple of cells, a small incandescent bulb, a switch and the relevant connections which together constitutes the flashlight circuit.
The only important few things to be taken into account in the above wiring are the compatibility of the involved units among each other.
The two cells which are joined in series contribute a potential difference of 3 volts, making it obvious for the bulb to be also rated at around this level, so the bulb is found to be of 3 volts. The current of the battery, which is another prime factor is also considered, given in some AH (Ampere Hour), is also matched with the bulb so that the illumination lasts for quite some time with optimum results.
Now suppose a larger flashlight with four of these cells, 1.5 volts each, together producing a potential difference of 6 volts. For this we would require a 6 volt bulb as the above 3 volt bulb would get burnt off within seconds and wouldn’t last the potential which is double its maximum rating.
However supposing you wanted to use 3 volts bulb with the above 6 volts, then as per the calculations, you would require two of them in series to match 6 volts across them without any danger. Thus, basically it’s just about adding up the light bulbs in series such that it matches or becomes close to the applied voltage across the connected load or the light bulbs.
It must be noted that, with incandescent bulbs or any resistive load, the type of current does not make any difference. Therefore, whether it’s an AC or DC, the results or rather the calculations remain exactly the same.
Making a String Light TORAN Using 12 Volt Torch Bulbs
For making the suggested string lights with 230 volts AC mains, we employ the same theory as explained above. In order to keep things clean and avoid too much of wiring mess, we choose light bulbs rated at 12 volts, instead of 3 volts.
Selecting 3 volt light bulbs would mean, 230 ∕3 = 77 numbers, which is huge and would require a hell lot of connections to be done. To avoid the clutter we rather use 12 volt devices, since dividing 230 by 12 gives around 20 numbers of light bulbs, which is a pretty manageable quantity as far as knitting them together is concerned.
Wire – 14/36, 10 meters or as per the required length.
Soldering Iron – 25 watt, 230 volts,
Solder wire – 60/40, 18 SWG,
Solder Paste also called flux.
Light Bulbs – 12 volts, 100 mA torch bulbs or similar.
Two pin plug – 1No.
As shown in the above string light circuit diagram, we can see that the bulbs are simply connected in series, end to end in sequence, until two wire terminate from the “string” which are connected to the supply mains outlet.
Usually the metal cylindrical body of the bulb forms one of the terminals, while the bottom soldered point forms the second electrical termination of it. These two points are the only places where the wires need to be soldered.
For proper soldering results, the portions must be perfectly cleaned using sand paper, however the use of solder paste itself is enough to make the soldering without the need of much cleaning.
Initially, the wire pieces must be cut and stripped as per the desired length, then the wire ends can be dipped in solder paste so that it may be soldered on the shown areas by touching the wire end and the soldering iron hot tip filled with molten solder simultaneously. The point will sizzle; hold the wire in place until the solder solidifies, holding the wire end firmly in place.
Finish the assembly procedure with the above steps to finally complete the light string or the toran.
In this case it simply needs to connect the bulbs in parallel and not in series. Use holders for better convenience. If bulb holders are used, the need of soldering is simply eliminated.
CAUTION - SINCE THE STRING LIGHT OPERATES AT AC MAINS POTENTIAL, ALL EXPOSED AREAS OF THE BULBS MUST BE APPROPRIATELY SHIELDED OR COVERED WITH INSULATING PLASTIC CAPS OR SIMILAR ENCLOSURES, NOT FOLLOWING THIS CAN RESULT IN SEVERE ELECTRIC SHOCK OR EVEN DEATH TO ANYONE TOUCHING IT IN POWERED POSITION.