How to Make a Simple LED Bulb Circuit

LED lights have gained a lot of popularity recently.

Another name for them is LED bulbs or solid state lighting.

Due to their significant lower power consumption i.e between 0.5 and 3 watts compared to other bulbs these lights are excellent for reducing electricity costs.

These bulbs were not as bright as some ten year ago but one can still make its own simple LED bulb circuit using this tutorial.

We will discuss how to assemble the LED lightbulb with various color options along with its advantages.

What is a LED Bulb Circuit:

An LED bulb circuit is an electrical circuit that supplies power and regulates the LED light bulbs

LED lights use semiconductor technology to create light making them more energy efficient than standard incandescent or fluorescent bulbs.

Converting electrical power into light, controlling current and offering extra features like color shifting or dimming are all handled by the components inside an LED bulb.

Circuit Working:

Parts List:

Every year the power and light brightness of LEDs grow due to their rapid technological advancement.

White LEDs are preferred choice for many applications which offer various light temperatures from warm white resembling conventional bulbs to daylight 2700 to 10,000k.

The selection between location and diffused LEDs also includes a range of radiation angles from 10° to 150°.

As technology progresses the price of LEDs continues to decline accompanied by an increase in brighter efficiency.

An online tool are available to make the conversion from brightness to light flow easy.

Power Supply:

A sufficient power source is necessary when using LED bulbs that are powered by the mains.

Because transformers are not the best option for low power and tiny sizes capacitance based power supplies are often used.

The best class X2 capacitor is one with an AC voltage of 250V which is used to reduce inrush current with a series resistance of 220Ω to 2.2kΩ.

After turning OFF a parallel security resistor of about 1M ensures capacitor discharges.

A tiny bridge diode rectifies the lower voltage.

With a common LED size of 5mm an online tool allows for calculating component values for LED bulbs.

Formulas and Calculations:

Following are the formulas with calculations for Simple LED Bulb Circuit:

Here we can estimate the current output of a transformerless power supply with a 0.33uF capacitor for two common mains frequencies: 50Hz and 60Hz.

Here is the calculation mentioned below:

Capacitance (C): 0.33 microFarads (uF) = 0.33 x ^10-6 Farads (F)

Formula: Xc = 1 / (2 * π * f * C)

where,

• Xc is the capacitive reactance in ohms Ω
• π (pi) is a mathematical constant which is around 3.14159
• f is the mains frequency in hertz Hz

Calculations:

For 50Hz Mains:

• Xc_50Hz = 1 / (2 * π * 50Hz * 0.33 x ^10-6F)
• Xc_50Hz = 9.55 kΩ (kilo-ohms)

For 60Hz Mains:

• Xc_60Hz = 1 / (2 * π * 60Hz * 0.33 x ^10-6F)
• Xc_60Hz = 7.96 kΩ (kilo-ohms)

We can calculate the current using the following formula as the capacitor serves largely as a reactance in the circuit:

I = V_in / Xc

where,

• I is the current in milliamps mA
• Vin is the mains voltage

Important Reminder:

Not all circuit elements are taken into account by this simple technique.

Also one should never measure mains voltage yourself for safety reasons.

Assuming a common mains voltage of 120V (US) or 230V (Europe) here is a rough estimate of the current output:

• For 50Hz (120V or 230V): I = Vin / Xc_50Hz = 12.6 mA (120V) or 24 mA (230V)
• For 60Hz (120V or 230V): I = Vin / Xc_60Hz = 15.1 mA (120V) or 29 mA (230V)

Note:

These are only the estimates because of safety margins, power dissipation and capacitor quality the actual current output might be less.

For the majority of LEDs a transformerless power supply with a 0.33uF capacitor most certainly wont produce enough current.

How to Build:

How to Make a Simple LED Bulb Circuit are the following steps needs to be followed:

Choosing an LED:

• Select the LED color, value and features that one needs such as current, brightness, and angle.

Design of the Power Supply:

• Select the type of power supply by keeping a note of the number of LEDs and their power needed.
• Use an X2 capacitor in a capacitance based power supply to reduced power consumption.
  Formula: Q = CV
• where Q is charge, C is capacitance and V is voltage.

Calculating Resistors:

• To reduce inrush current choose a series resistor between 220Ω and 2.2k.
• R = V/I is Ohms Law.
• where I stands for current, V for voltage and R for resistance.

Safety precautions:

• To help in the capacitors discharge a parallel security resistor of around 1M must be added.
• Add a fusible resistor or fuse to protect the input.

Correction:

• A little bridge diode can be used to correct the lower voltage.

LED Connection:

• To adjust for the decreased voltage use a little bridge diode.
• LEDs are designed for handling a 20mA current.
• Calculate the value of the capacitor using the the formula:
• C is equal to I * Δt / ΔV.
• where I stands for current, Δt for time, ΔV for voltage and C for capacitance.
• LEDs are connected in series up to a particular value, such as 20mA without affecting component values.
• Change the capacitors capacity for greater values.

Construction:

• Connect the components on a circuit board ensuring proper insulation and spacing.
• Add the LEDs into the chosen base or socket.
• Use electrolyte to improve the source and by removing stroboscopic effects and protecting against inrush currents for better performance.

Safety Precautions:

• Follow safety measures when working with mains voltage.
• Protect conductive parts to prevent electric shock.
• Display a warning about the lack of galvanic isolation and the associated risks.
• Design the circuit at ones own risk.

Note:

• Actual values may differ depending on the components used as this article offers an overall summary.
• Always verify that component ratings match to safety regulations and if necessary seek an expert advice.
• There are risks involved in building electrical devices thus safety should be used at every steps.

References:

LED lamp

LED-Lamp Design for Renewable Energy