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Old 07-05-2012, 05:45 AM   #11
theblondskeleton
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Default Wiring

11. Emitter Wiring

I debated even putting in this section, as there is such an abundance of info on this subject that there are degrees and licensing processes in place to assure that the professionals understand what they are doing. Essentially, if you don't have at least a working knowledge of electrical wiring before you create your fixture, you have no business building one. I have to admit that I still have a fair amount to learn, myself. What I will provide is a few basic comments as it pertains to LED fixture construction. This includes just enough info to get you started, and is by no means considered complete.

*Please let me know IMMEDIATELY if any aspect of this section is incorrect.

Electrical wiring is dangerous. Build at your own risk. If you do not understand what you are doing, you risk injury to yourself or others and property damage or destruction by fire. It is highly recommended that you consult a licensed electrician before you commit to any aspect of your build. The author is not responsible for any injury, death, accident, fire, damage or destruction to personal or real property as a result of creation of a device using this information. This guide is intended as a research reference only.

What is the difference between Series and Parallel wiring?
Series and parallel wiring are different ways to apply current to your emitters. Both can be used in assembling your fixture, but each has its individual purpose.

Series

This is the recommended way to connect your emitters so that they receive current. To achieve this, your emitters are wired to the power source by connecting the + of the first emitter to the power source, and the - to the + of the next emitter. The emitters are connected this way until the forward voltage limit is reached (see Driver section for more info on forward voltage), and the - for the last emitter is wired to the - end of the power source.

Here is a diagram showing series and parallel as well as an example of a bad idea.

It is important not to wire an emitter in reverse, as it is possible to destroy the emitter by applying current in the wrong direction.

Parallel

It is not recommended to wire your emitters in parallel, unless you are putting together 2 strings of series-connected emitters to run from one driver. This splits the current between the two strings, running each at approximately half the current provided by the driver - provided the forward voltage limit for the driver is observed.
What kind of wire should I use for my fixture?
20-gauge wire is often used to connect each emitter, but heavier-duty wire is required to span long distances between the driver and the emitters. Please be sure to observe your local electrical codes when wiring your fixture!!! If you are uncertain about ANY aspect of this process, consult a professional electrician.
How do I solder these emitters together?
For this, I recommend any of the many soldering tutorials available at the vendor websites, or taking a beginning electronics class in your area. This is a great skill to have, and most people can do this with a little knowledge and practice.

Solder Type

For LED fixtures, it is frequently recommended to use about a 60/40 rosin-core solder to attach wires to the emitters, as this is pretty user-friendly. Rosin-core solder contains lead, so be sure to observe proper procedures when using it, and to keep it away from children or pets.

Solder Temperature

Different methods will require different soldering techniques. It is important to observe that duration of applied heat is your emitter's worst enemy when it comes to life span. It's wisest to use a higher-wattage iron (I have read 30W+ will do the job, but often read that 60W is recommended) as it is able to provide more constant heat, or a fancy soldering station with temperature control. Recommended temps to apply solder can be found on vendor websites like LED Groupbuy or Rapid LED's tutorial sections.

Tinning

It is highly advisable to pre-tin your connections before you put everything together, as it reduces the amount of time heat is applied to your emitters. Pre-tinning is the process of applying a small amount of solder to the surfaces to be soldered together (the pads of the emitter star and the connecting wire). Do do this, there are as many techniques as there are individuals who do it. I simply melt a bead of solder with the iron tip, and transfer it to the surface to be tinned. Others heat the surface and melt the bead into it. Some use helping hands to assist, others tin after applying the emitters to the heat sink.

This last method requires the higher-wattage or temperature controlled irons, as the heat sink will do its job by conducting any heat applied away from the emitter, cooling the pads much more quickly. As we know, heat is our enemy, so with a low-wattage iron, you may need to apply heat much longer than is advisable.
Do I have to solder the connections?
Not necessarily. If you are terribly uncomfortable with wiring, there are options available to purchase clips from certain vendors that connect wires to particular brands and models of emitters. These eliminate the need to solder any connections. It is highly recommended to use solid-core wire with these connectors to ensure a solid connection. The major drawback is that they drive up the price of your build. Soldering is still the recommended method of connecting your emitters, and is a pretty easy skill to learn. Some vendors even provide tutorials on how to solder properly to avoid "cold solders," and other pitfalls of the process.

More info on the quality of these connectors would be helpful!

Last edited by theblondskeleton; 08-21-2012 at 08:56 PM.. Reason: Added info
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