The post elaborately expleian how to buil a simple LED bulb using many LEDs in series and powering them through a capacitive power supply circuit
Why use LEDs
- LEDs are being Incorporated in vast magnitudes today for everything that may involve lights and illuminations.
- White LEDs have especially become very popular due to their mini size, dramatic illuminating capabilities and high efficiency with power consumptions. In one of my earlier post I discussed how to make a super simple LED tube light circuit, here the concept is quite similar but the product is a bit different with its specs.
- Here we are discussing the making of a simple LED bulb CIRCUIT DIAGRAM, By the word "bulb" we mean the shape of the unit and the fitting secs will be similar to that of an ordinary incandescent bulb, but actually the whole body of the "bulb" would involve discrete LEDs fitted in rows over a cylindrical housing.
- The cylindrical housing ensures proper and equal distribution of the generated illumination across the entire 360 degrees so that the entire premise is equally illuminated. The image below explains how the LEDs needs to be installed over the proposed housing.
Image credit: https://www.sharplumi.com/en/userfiles/20100913191605380.jpg Circuit Description The circuit of a LED bulb explained here is very easy to build and the circuit is very reliable and long lasting.
The reasonably smart surge protection feature included in the circuit ensures an ideal shielding of the unit from all electrical power ON surges.
How the Circuit Functions
- The diagram shows a single long series of LEDs connected one behind the other to form a long LED chain.
- To be precise we see that basically 40 LEDs have been used which are connected in series. Actually for a 220V input, you could probably invorporate around 90 LEDs in series, and for 120V input around 45 would suffice.
- These figures are obtained by dividing the rectified 310V DC (from 220V AC) by the forward voltage of the LED.
- Therefore, 310/3.3 = 93 numbers, and for 120V inputs it's calculated as 150/3,3 = 45 numbers. Remember as we go on reducing the number of LEDs below these figures, the risk of switch ON surge increases proportionately, and vice versa.
- The power supply circuit used for powering this array is derived from a high voltage capacitor, whose low reactance is exploited for stepping down the high current input to a lower current suitable for the circuit.
- The two resistors and a capacitor at the at the positive supply are positioned for suppressing the initial power ON surge and other fluctuations during voltage fluctuations. In fact the real surge correction is done by C2 introduced after the bridge (in between R2 and R3).
- All instantaneous voltage surges are effectively sunk by this capacitor, providing a clean and safe voltage to the integrated LEDs at the next stage of the circuit.
CAUTION: THE CIRCUIT SHOWN BELOW IS NOT ISOLATED FROM THE AC MAINS, THEREFORE IS EXTREMELY DANGEROUS TO TOUCH IN POWERED POSITION.
R1 = 1M 1/4 watt
R2, R3 = 100 Ohms 1watt,
C1 = 474/400V or 0.5uF/400V PPC
C2, C3 = 4.7uF/250V
D1---D4 = 1N4007
All LEDs = white 5mm straw-hat type input = 220/120V mains...
The above LED bulb lacks a genuine surge protection feature and therefore could be severely prone to damage in the long run....in order to safeguard and guarantee the design against all sorts of surge and transients, you can refer to the following concepts and implement any one of these in the above simple design:
The LEDs in the above discussed LED bulb circuit can be also protected and their life increased by adding a zener diode across the supply lines as shown in the following image.
The zener value shown is 310V/2 watt, and is suitable if the LED bulb includes around 93 to 96V LEDs. For other lower number of LED strings, simply reduce the zener value as per the total forward voltage calculation of the LED string.
For example if a 50 LED string is used, multiply 50 with the forward drop of each LED that is 3.3 V which gives 50 x 3.3 = 165V, therefore a 170V zener will keep the LED well protected from any sort of voltage surge or fluctuations....and so on
Video clip showing an LED circuit circuit using 108 numbers of LED (two 54 LED series strings connected in parallel)
Simple LED Bulb using 1 watt LEDs.
A simple high power LED bulb can be built using 3 or 4 1 watt LEDs in series, although the LeDs would be operated only at their 30% capacity, still the illumination will amazingly high compared to the ordinary 20mA/5mm LEDs.
Moreover you won't require a heatsink for the LEDs since these are being operated at only 30% of their actual capacity.
Simple LED Lamp for Home Decor, Made by Using Ordinary LEDs, Powered by a 12V AC/DC Adapter:The following images were sent to me by one of the keen followers of this blog Mr.Ishaan Pathania. The shown prototype of a simple LED lamp was built and tested successfully by him: