CFL bulbs are gradually being phased out in favor of DIY LED Light Bulbs (LED Lamps), which are experiencing growing popularity. As the cost of LED light bulbs continues to decline, people are increasingly adopting LED lamps to illuminate their homes and workplaces. In this project, we will explore the construction of a DIY LED Light Bulb or DIY LED Lamp using an old LED Lamp housing.
The design of the LED Driver holds significant importance in this DIY LED Light Bulb project. The LED Driver can be created using one of two methods: employing a switching mode power supply or opting for a traditional transformer-based linear regulator.
However, for our DIY LED light bulb, we will be devising a transformerless power supply to serve as the LED Driver. Notably, this type of power supply for LED Lamps is gaining popularity, particularly for lower wattage LEDs.
Warning: This DIY LED Light Bulb will work directly from the main supply i.e. 230V AC. You need to be very careful when working on AC Supply.
Warning: Designing Transformer less power supply without the knowledge of how the components work can be fatal.
- DIY LED Light Bulb Circuit Diagram
- Components Required for DIY LED Light Bulb
- Component Description
- X – Rated Capacitor
- Circuit Design of DIY LED Light Bulb
- PCB Design of DIY LED Light Bulb
- Assembling the LED Light Bulb
- Working of the LED Light Bulb
DIY LED Light Bulb Circuit Diagram
Components Required for DIY LED Light Bulb
- C1 – 135J 400V Metal Film Capacitor
- B1 – Bridge Rectifier (4 Diodes can be connected in Full wave Rectifier mode)
- C2 – 22µF 35V Electrolytic Capacitor
- R1 – 100KΩ Resistor (1/4 Watt)
- LED 1 to 12 – 8mm LEDs
X – Rated Capacitor
The pivotal element within the Transformerless Power Supply Design for the DIY LED Light Bulb is the X-Rated Capacitor, a metal film capacitor frequently employed as a safety component.
This X-Rated capacitor is positioned between the line and neutral. In the event of an overvoltage causing the capacitor to malfunction, it will fail as a short circuit, leading to an excessive current flow that subsequently triggers the fuse. This protective mechanism effectively prevents any electrical shocks.
Circuit Design of DIY LED Light Bulb
To begin, the primary power supply is routed to the metal film capacitor. The opposite end of the capacitor is linked to the AC input of a bridge rectifier. For added safety precautions, it’s advisable to include a 100Ω 1W Resistor in series with the X-Rated Capacitor, serving as a protective fuse (please note that this resistor is not depicted in the circuit).
NOTE: If you do not have a bridge rectifier, you can connect 4 PN Junction Diodes (like 1N4007) in full wave rectifier mode.
The Neutral from the AC Power Supply is connected to the other AC Input of the Bridge Rectifier. A capacitor, denoted as C2, receives the rectified output. In series, twelve 8mm LEDs are connected across this capacitor.
R1 serves the purpose of a bleeder resistor, and its function is to discharge the capacitor in situations of power failure or if any of the LEDs malfunction.
Please note that we disassembled a malfunctioning LED light bulb and reconstructed a circuit that closely resembled the one we designed. The primary difference lies in their use of SMD components for LEDs and the bridge, whereas our design incorporated through-hole components for obvious reasons.
PCB Design of DIY LED Light Bulb
Assembling the LED Light Bulb
Assemble all the components following the provided layout and proceed with soldering them into place. We acquired an empty LED Housing from a previous LED Lamp. Once the PCB assembly was completed, we securely positioned the board within the LED Housing along with all the associated wires.
Working of the LED Light Bulb
Let’s delve into the operational principles of this simple LED light bulb.
LEDs demand very minimal current to operate efficiently. In traditional transformer-based regulated power supplies, series resistors are typically employed to regulate and govern the current flow. However, in the case of a transformerless power supply, the X-Rated Capacitor serves as the component responsible for controlling or limiting the current.
The total current available within the circuit is restrained by the capacitor’s reactance since it is connected in series with the AC supply. The formula to calculate the reactance of a capacitor is as follows:
XC = 1 / (2πFC) Ohms, where F represents the frequency of the supply, and C is the capacitance of the capacitor.
In our specific scenario, we utilized a 1.3µF Capacitor. Consequently, the reactance of this capacitor is computed as:
XC1 = 1 / (2 * π * 50 * 1.3 * 10^-6) = 2449.7, approximately 2450 Ω.
Thus, the current flowing through this capacitor can be determined as follows: I = V / XC1, yielding a current of 93.8mA when V is 230V.
Subsequently, the current-limited AC supply is directed to the Bridge Rectifier, resulting in an output of 230V DC. This DC voltage is subsequently applied to a filter capacitor rated at 35V. However, it’s important to note that the peak-to-peak ripple voltage across Capacitor C2 approximates 44V.
This voltage is then supplied to a series of 12 LEDs. Each LED operates on approximately 3.7V, which aligns with the rated voltage for 8mm LEDs.
Regarding power output, the collective power generated by the LEDs amounts to approximately 4W.
Important Note: This project is just a demonstration of How to design an LED Light Bulb and How an LED Light Bulb works. The method mentioned in this project might not be suitable for practical usage.
Also, the project involves working around 230V AC Mains Supply. You need to be extremely careful when working with AC Supply.