Hopefully those looking for practical information on electrical circuits and wiring LED components found this guide first. It’s likely though, you’ve already read the Wikipedia page about Series and parallel circuits here, maybe a few other Google search results on the subject and are still unclear or wanting more specific information as it pertains to LEDs.
With years of providing LED education, training and explaining the electronic circuit concept to customers, we have gathered and prepared all the critical information needed to help you understand the concept of electrical circuits and their relationship to LEDs.
First things first, don’t let electrical circuits and wiring LED components sound daunting or confusing – connecting LEDs correctly can be simple and made easy to understand if you follow this post. Lets get started with the most basic question…
What type of circuit should I use?
Is one better than the other…Series, Parallel or Series/Parallel?
The requirements of a lighting application often dictate what type of circuit can be used, but if given the choice, the most efficient way to run high power LEDsis using a series circuit with a constant current LED driver. Running a series circuit helps to provide the same amount of current to each LED.
This means each LED in the circuit will be the same brightness and will not allow a single LED to hog more current than another. When each LED is receiving the same current it helps eliminate issues like thermal runaway.
Don’t worry, a parallel circuit is still a viable option and used often; later we will outline this type of circuit.
First though, lets wrap our heads around a series circuit:
3 LEDs in-series circuitOften referred to as ‘daisy-chained’ or ‘looped’ the current in a series circuit follows one path from start-to-finish with the Anode (positive) of the second LED connected to the Cathode (negative) of the first.
The image to the right shows an example: To wire a series circuit like the one shown, the positive output from the driver connects to the positive of the first LED and from that LED a connection is made from the negative to the positive of the second LED and so on, until the last LED in the circuit. Finally, the last LED connection goes from the negative of the LED to the negative output of the constant current driver, creating a continuous loop or daisy chain.
Here are a few bullet points for reference about a series circuit:
Same current flows through each LED
The total voltage of the circuit is the sum of the voltages across each LED
If one LED fails, the entire circuit won’t work
Series circuits are easier to wire and troubleshoot
Varying voltages across each LED is okay
Powering a series circuit:
The loop concept is no problem by now and you definitely could figure how how to wire it, but how about powering a series circuit.
The second bullet point above states, “The total voltage of the circuit is the sum of the voltages across each LED”. This means you have to supply, at minimum, the sum of the forward voltages of each LED. Lets take a look at this by using the above circuit again as an example and lets assume the LED is a Cree XP-L driven at 1050mA with a forward voltage of 2.95V. The sum of three of these LED forward voltages is equal to 8.85Vdc. So theoretically, 8.85V is the minimum required input voltage to drive this circuit.
In the beginning, we mentioned using a constant current LED driver because these power modules can vary their output voltages to match the series circuit. As LEDs heat up their forward voltages change, so it’s important to use a driver that can vary its output voltage, but keep the same output current. For a deeper understanding of LED drivers take a look here.
But, in general it’s important to make sure that your input voltage into the driver can deliver an output voltage equal to or greater than the 8.85V we figured above. Some drivers require inputting slightly more to account for powering the internal circuitry of the driver (the BuckBlock Driver needs a 2V overhead), while others have boosting (FlexBlock) features that allow you to input less.
Hopefully you are able to find a driver that can accomplish your LED circuit with the diodes in-series, however there are circumstances that might make it impossible. Sometimes the input voltage might not be enough to power multiple LEDs in-series, or maybe there are too many LEDs to have in-series or you just want to limit the cost of LED drivers. Whatever the reason, here is how to understand and configure a parallel LED circuit.
Where a series circuit receives the same current to each LED, a parallel circuit receives the same voltage to each LED and the total current to each LED is the total current output of the driver divided by the number of parallel LEDs.
Again, don’t worry, here we will see how to wire a parallel LED circuit and that should help tie the ideas together.
parallel-circuitIn a parallel circuit all the positive connections are tied together and back to the positive output of the LED driver and all the negative connections are tied together and back to the negative output of the driver. Lets take a look at this in the image to the right.
Using the example shown with a 1000mA output driver, each LED would receive 333mA; the total output of the driver (1000mA) divided by the number of parallel strings (3).
Here are a few bullet points for reference about a parallel circuit:
The voltage across each LED is the same
The total current is the sum of currents through each LED
The total output current is shared through each parallel string
Exact voltages are required in each parallel string to help avoid current hogging
Now, lets have some fun and combine them together and outline a Series/Parallel Circuit:
As the name implies a series/parallel circuit combines elements of each circuit. Lets start with the series part of the circuit. Lets say we want to run a total of 9 Cree XP-L LEDs at 700mA each with Series Parallel Circuit Diagram a voltage of 12Vdc; the forward voltage of each LED at 700mA is 2.98Vdc. Rule number 2 from the series circuit bullet points proves that 12Vdc isn’t enough voltage to run all 9 LEDs in-series (9 x 2.98= 26.82Vdc).
However, 12Vdc is enough to run three in-series (3 x 2.98= 8.94Vdc). And, from the parallel circuit rule number 3 we know that total current output gets divided by the number of parallel strings. So, if we were to use a 2100mA BuckBlock and have three parallel strings of 3 LEDs in-series, then the 2100mA would get divided by three and each series would receive 700mA. The example image shows this set-up.
If you are trying to set up an LED array this LED circuit planning tool will help you decide what circuit to use. It actually gives you several different options of different series and series/parallel circuits that would work. All you need to know is your input voltage, LED forward voltage and how many LEDs you wish to use.
The downfall of multiple LED strings:
One thing to keep in mind about running parallel and series/parallel circuits is that if a string or LED burns out, the LED/string will then be cut out of the circuit so the extra current load that was going to that LED will then be distributed to the rest.
This isn’t a huge issue with larger arrays as the current will be dispersed at smaller amounts but what about a circuit with just 2 leds/strings? The current would then be doubled for the left over LED/string which might be a higher load than the LED can handle resulting in a burn out and ruining your LED! Make sure you always keep this in mind and try to have a set up that wouldn’t ruin all your LEDs if one happened to burn out.
How To Connect Multiple LED Strips To one Power Source in A Jiffy?
Do you know how to connect multiple LED strips to one power source? Well, I have noticed that most suppliers of LED strip lights don’t provide clear and simple installation guide advice to their clients. Many of them make the assumption that you already have some prior knowledge of the lighting devices before you go out of your way to purchase them.
However, you may be completely new to the field, and you are buying them with the simple reason of impressing your cronies who will be attending your birthday bash over the weekend.
Step by step instructions
Step 1: Determine the type of circuit to use
So, which one is better: series, parallel or hybrid? The power requirements of any lighting system determine the type of circuit to employ. You won’t need to worry if you have not been to an electronics class since circuitry is fairly easy to grasp.
The easiest circuit type you can use to fix your LED strips is the series mode. The current in this circuit follows a single path from start to end. The positive end of one LED strip connects to the negative end of the next, and the series continues to both ends of the LED strip splitter which then plugs into the mains supply in the wall. The series circuit is also flexible as you can create almost any pattern with your strips.
Step 2: Connecting the LED strips
Learning how to connect multiple LED strips to one power source shouldn’t necessarily jade you if you opt for the series circuit. All you need to do is to identify the anode (positive) and the cathode (negative) ends of each LED strip. It shouldn’t be too much of a technicality since most LED strip manufacturers label those points accordingly.
You will need to determine which shape you want the lights to take. The pattern may depend on the area or object you want to illuminate. Having chosen your preferred shape, proceed to join the anode of the first strip to the cathode of the next until you exhaust all the strips you have bought. You now have a length of several strips joined together from end to end. You can now connect the ends of the series of strips to the 2.1 mm female plug that came with the equipment before plugging it into its male counterpart for powering.
Step 3: Checking the power requirements of the strips
You need to keep an eye on the power rating on the LED strips before you plug them into a power source. The total amount of power required is the sum total of the voltage needed by each strip in the series. Remember that in the series circuit, the same amount of current flows through from one end to the other, but the voltage will vary at each point.
Consequently, you will need to ensure that the power output is enough to power all the strips to avoid compromising on the quality of the light output. If the power outlet is too much, it may damage your strips, rendering them unusable. Take note that these strips are expensive, and you wouldn’t want to spoil your party by damaging them even before they have been of benefit to you.
Step 4: Placement of the LED strips
One factor to consider when placing the LED strips is the power source. Whether you wish to light up the hallway, the bookshelf or the kitchen cabinet, proximity to the nearest power outlet is of paramount importance.
It would be better to have the power source as close as possible to the placement of the strips to make for easy connections and to avoid using too much wire. The main purpose for the single source of power is to avoid creating a hideous tangle of cables in the house. Locating the nearest power source ensures a shorter cable hence reduced possibility of tangling.
Step 5: Checking the connections
You aren’t looking forward to an electric accident. It may likely occur if the joints you have made between the strips on the connectors are not proper. Before plugging them into the mains supply, you need to go over each joint to check for errors in connection, loose joints, or any hanging wire threads. To be on the safe side, take your time to analyze each node to ensure that everything is perfect. Some of the areas to look out for include the anodes and cathodes, and if they are in good working condition.
You also need to check each of your LED strips for visible defects, which may be a pointer to something wrong in their general make-up. If you have done any soldering, make sure the solder is firm and solid to ensure a steady joint.
Step 6: Plugging into the power source
When you are absolutely sure that your joints are fail-safe, you can consider plugging in. but before you plug in, you should ensure that various devices are in place. Have the 2.1 mm female connector as well as its corresponding male counterpart to ensure seamless connection to the power supply.
Plug the female part into its male correspondent and switch on the switch to see if the strips light up. If your connections are good and all then devices in good working order, the LED strips should light up brilliantly. Once you have the LED strips glowing brightly, you can switch them off and wait for the big day, or simply let them dazzle the night away.
Did you enjoy this tutorial? Well, this list is important to me because it helped me set up my LED strips without any problem despite having been a complete novice in matters electricity. It is my hope that this tutorial goes a long way to help you since I have come across many buyers of these strips who are unable to set them up by themselves and have to incur additional expenses to hire a technician.
This tutorial not only saves your precious hard earned dollars but also a safe and easy way to connect your strips at home. What do you think about this article?
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