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Wiring a Simple LED Series Circuit

Michael Houlder

So, you've decide on your LEDs! Great!  

You selected the correct driver! Happy Days!  

You have deliberated for ages over the best arrangement for your array and mounted everything to a heatsink. OK you flying!  

No what happens next? Well unsurprisingly you probably want to wire the things up and be dazzled with you knew lighting system. At Future Eden, we frequently receive questions about how this is done so we though it prudent to provide you a little instruction on the most typical method for wiring from a constant current driver - the humble series circuit 

Now most of you reading this will probably recognise the phrase from a rudimentary electronics lesson at school. Indeed, it is the simplest electrical circuit you can create and in most small LED projects using a constant current driver is the route to follow to get things up and running. 

Just to understand the principle, I have included and schematic below for how this translates to a 6 LED array. 

High pwer 3W LED wired in series on heatsink with constant current driver power supplyNow as I say the principle is incredibly simple. You run a cable from positive cable of the driver to the positive pad on the LED. You then a further cable from negative pad of the LED to the positive of the next. You then continue this chain of + to - all the way back to the negative (ground) cable of the driver.

Once this is turned on charge can then flow from positive to negative through each LED in the correct direction and all being well they will all light! Simples!

Now of course even with the simplest of circuits problems can arise and I have listed several potential problems you might encounter below: 

  

Pitfalls and the Flashing Lights of Doom

Despite the simplicity of this circuit there are few common errors to watch out for, which are often accompanied by either a sad looking unlit LED or very often a pulsing/flashing array. If you experience a flashing LED please don't panic, you have not bought a component for a wedding disco, it is simply the driver cutting the power to the circuit as it has detected a fault. The flashing results from the tripping and resetting of the circuit protection in the driver as it cuts the power and then tries to turn itself back on only to find the fault in the circuit still exists so it cuts the power once more. This will continue until the problem is fixed.  Of course, if the lights are flashing you should turn off the power at once and diagnose and fix the problem, which is likely to be one of the following:  

Incorrect LED polarity - Simply put, getting the LED the wrong way around in the circuit. I have done this more times than I care to mention and you should check and double check everything before you switch on to make sure the wiring follows the concept above. Any incorrect wiring will result in the circuit not working or worse still damaging the components which are designed only for charge to flow one way through them.  

Accidentally wiring in Parallel - This is something that is again very common. Due to the number of solder pads on the star PCBs, it is often wrongly assumed you need to wire in parallel with two cables between each LEDs. Whilst this is of course fine if you are trying to build a parallel circuit when using an appropriate supply, however this is rarely the way to go with the constant current driver typically used in small LED arrays. 

Shorting on the heatsink - Another common problem. In the rush to get everything up and running we often see projects that have heavily soldered pads with solder that has split over the edge and is touching the heatsink or the back of a PCB. As we all know aluminium will conduct electricity so any contact between the solder and the metal could easily cause a short. Once again you will likely see the Flashing lights of doom and you will need to resolder to remove the unwanted connection.  

Whilst this list isn't exhaustive it highly several common errors. If you experience problems which can’t be fixed by correcting the above, we will of course be more than happy to work the problem through with you. Just drop us a line on our email or online chat function and one of our staff will happily help you. 

Anyway, I hope this has been informative! If you need anything else, you know where we are!  

Good luck to everyone with their projects

 

Mickey and the Future Eden Team 



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