There are some brain maniacs that like everything new, especially when this is something very useful. However initially everything new is always expensive and have a lot of issues.
The first thing you need to know about LED bulbs that they can be divided into two groups – with simplified constant current driver and full featured. Constant current driver (or just driver) is required to convert AC current into constant DC current that power LEDs. Simplified driver uses schematics with ballast capacitor and looks as following:
Majority of lamps with such driver are called “corn” bulbs and looks as following:
Lamps like on the picture above consists from 54 so-called 5050 type LEDs that consumes 0.25 W and emits 15 lumen each. Ideal power dissipation of such lamp is 13.5 Watt and 810 lumen which can be compared to 75 W legacy lamp bulb. However in reality this lamp is producing something about of 400 lumen and consumes 5 Watt. Simplified driver really suffers. It converts the sine wave AC voltage doubling its frequency to 100 (120) hertz from which, due to their nature, LEDs will emit light only part-time on the tops of half-cycles of the original sine wave as shown below:
Is it good or bad? Well, yes and no. The main issue is flickering. We might not see it but our mind does. Another disadvantage is that these lamps are not much more efficient in power consumptions than standard energy-saving fluorescent lamp bulbs.
Well, then do we have any advantages with such bulbs at all? Sure!. First of all they are inexpensive (cheap!). Secondly, from an electrical point of view that they introduce to power sources they are very close to plain old legacy lamps and provide resistive load whereas energy-saving fluorescent lamps introduce reactive load. Roughly speaking resistive load means that right from the switching on this lamp type will consume constant current. In contrast reactive load usually means a surge current consumption at the start, followed by stabilization. This behaviour might be very important for some power switching devices such as electronic wall switches.
Lets return back to our two main types. Full featured LED driver looks as follows:
You can see here much more components and even some IC chips. This driver converts AC current into constant direct current ideal for LEDs. Lamps with full featured driver usually have a radiator or at least massive base and look something like this:
Comparing to use of dozens of LEDs in “corn” bulbs such bulbs are build using just few. However these few LEDs are working in full power. These lamps do not flicker and save almost twice as much electricity than fluorescent. But there are still some shortcomings, the more watts lamp exposes the bigger base and dimensions it will have. Sometime such bulbs looks more like a big flashlight than legacy bulb. Luckily Chinese engineering realized this weakness and came up with LED bulb forms like this:
What you need to know about these LED lamp bulbs. They are way more expensive, and therefore there is much higher risk of fraud. Cheating would be in declaring of much bigger power dissipation than it can provide in reality. To avoid this, we must be able to compare declared facts with reality. For example the first bulb was declared as 5 watt. If you look closely, we will see 3 petals by 2 LEDs on each, a total of 6 LEDs. LED type is usually listed in specs, but if not it can be usually recognized from pictures. LEDs are recognized as type 5050 which gives us 1.5 WATT and 90 lumen. This will be not enough even for a toilet. On the second lamp there are 48 LEDs of 3014 type, each with a capacity of 0.1 WATT and emitting 12 lumen. This will give us honest lamp with 5 WATT and about 600 lumen (can be matched to 60 W legacy bulb).
Finally, LED bulb form is not primary and single factor that allows us to differentiate lamps with simplified and full featured driver. The “corn” looking lamp can have good driver, and in opposite lamp with massive base might not have it. Precise criterion is the operating voltage supported by lamp. Full featured driver as a rule is designed to operate in a range from 110 to 265 volts. While the lamp with simplified driver can operate only bound to 220 or 110 volts (not both in the same time).