By Scott Watson

Apart from using the DC drive circuitry in some conditions, LEDs also make use of the AC Drive Circuitry.  DC circuitry is powered by batteries while the AC is powered by the electrical current.  In this write-up, LEDinside are going to be discussing some details concerning the practical aspects of AC drive circuitry meant for LEDs.

Actually, when your LED light is run off the electrical grid, the AC drive circuitry is simply used.  The power conversion of the AC power is known to be very complex than the DC version.  It is technically complicated. There are also various government regulations concerning the EMI emissions in AC drive circuitry.  There are some pieces of information you need to know about the AC drive circuitry.  Let's examine them.

Safety
This is the very first thing you must grab about the AC drive circuitry.  The AC drive is very deadly.  Before ever you do anything with the AC power source, you need to pay attention to given instructions.  Whether you are an electric engineer or a simple user of AC related devices, you need to be careful when work with the AC drive since it can be very dangerous.  It is highly recommended that you procure a kill switch and get it installed in your lab before you ever work on any AC power drive.  The Kill switch is a big red button you can install on the doorway. You can easily hit it with your fist while it goes ahead to turn off all the electrical outlets in your lab.  The light will still be on to show you the way to go.   The kill switch protects you from accidents that may occur as you work with the AC drive power source.

One of the dangerous aspects of AC power is known as fibrillation. It refers to the possibility of your heart muscles twitching in an uncontrollable manner.  If for instance you touch one side of the AC line with one hand and also touch the other side with the other hand, you can easily get electrocuted.  Again, if you touch the AC line with your hand while you stand barefooted, current can easily flow through your body and your feet to reach the ground. This can easily stop your heat from working.

You must be careful about your safety when you work on any AC drive circuitry meant for LEDs.  A simple 5 mA is even more than enough to create unpleasant shock.  To get yourself protected, you need to take note of the following tips:

•    Make sure you switch off the AC line before you work on any circuit

•    Do not presume anything when you work on an AC circuit. You must make sure the input voltage monitor is reading zero or you simply unplug the power source.

•    Always use an isolation transformer to safeguard yourself.  The transformer can be a little bit big and made of steel.  It has the function of providing isolation between the input AC line and its output.  In most cases, the output can be 120 VAC or it can as well be doubled.

•    Try using a fuse in your circuit. You can easily get power through the fuse but it has a limited time.  It helps you not to stay connected to the AC line for a long period.

•    Always keep one of your hands behind your back if you must touch any live circuit. This protects you a lot.  If you are able to keep one hand behind your back, you will not be able to create a circuit from one arm or across your heart.   Your heart can also be protected from the current.  You may also hold on to your belt for maximum safety.

•    Do not use cheaters.   They are simply AC adapters that convert three prong plugs to 2 prong plug.  They claim to offer isolation but in actual fact, they do not.

•    Try using insulation. It is simply the best safety measure to engage.

•    Create a danger sign and put it where people will see it.  This will help people to desist from touching the circuit.

•    Turn off the circuit especially when going out of the area to do something else.  This prevents unnecessary electrocution on anybody coming to see your work when you are not around.

•    You can also cordon off the area entirely especially if you are going to be leaving the AC circuit on all through the night.

The AC Line
The AC line is the next aspect you need to master very well. It refers to a very complex electrical environment. You need to know what the environment actually looks like before you can carry out any design in it.  In the first place, you have to discover what the voltage of the AC line is.  This usually varies according to continents and government regulations. In the US for instance, the acceptable voltage is 120 VAC. There is also 208 VAC allowed in US homes for dishwashers and other equipments. 480 VAC is used for industrial settings.   In the rest of the continents, 240 VAC is allowed.  In the US, 277 VAC is used to power fluorescent ballast fixtures. This is usually vital when designing LED replacements for such kind of light sources.  In any case, it is advisable that your LED circuit should be able to survive any voltage line that ranges from 0 – 135 VAC.  It should be able to work within this range and not outside the range. 

It is important to note that you are covered in the US market when you design your LED within the range of 0 – 135 VAC. However, for the rest of the world, you can use the 240 VAC to 265 VAC range.  You should also know that incandescent light bulbs are meant to suit specific countries.  You may need to consider this before you launch any design for different countries. You may try using the universal 120 VAC and 240 VAC to run the design.

In all, the practical AC Drive Circuitry for LEDs can be very complicated. There is a need to be safety conscious when you are working with the AC line.