This Simple AC Mains Powered LED Night Light Circuit that runs on AC mains power allows you to use bright white LEDs directly from a 230V AC supply, without needing a big transformer.
It is a reliable design that can support 24 super bright LEDs with each one using 50mA of current.
This small and efficient setup is a budget friendly way to light up your room at night.
The circuit cleverly uses a capacitive power supply, a bridge rectifier and a filter capacitor to power the group of LEDs effectively.
Circuit Working:
Parts List:
| Component Type | Value / Specification | Quantity |
|---|---|---|
| Resistors | 470k, 0.25W | 1 |
| 100Ω, 0.5W | 2 | |
| Capacitors | PPC 1µF, 400V | 1 |
| Electrolytic 10µF 160V | 1 | |
| Semiconductors | Bridge Rectifier 1N4007 400V 1A | 1 |
| White Straw Hat LEDs | 24 |
The circuit works mainly on the idea of a capacitive power supply.
In this design capacitor C1 acts as a reactive dropper which helps control the alternating current while keeping power loss low.
The bridge rectifier D1 to D4 which can handle 400V and 1A is important for changing the alternating current into direct current.
After this change a capacitor C2 is used to smooth out the direct current making it more stable.
Also, R1 and R2 resistors are placed in the circuit to limit the inrush current protecting the other parts of the circuit.
To meet the voltage and current needs there are 24 bright white LEDs arranged in a series parallel setup.
Formulas with Calculations:
Below mentioned are the formulas with calculations for Simple AC Mains Powered LED Night Light Circuit:
Current Limiting Through Capacitor:
Capacitive reactance:
Xc = 1 / (2 * π * f * C1)
Xc = 1 / (2 * 3.1416 * 50Hz * 1µF)
Xc = 3180Ω
Mains voltage is 230V AC, so the current:
I = V / Xc
I = 230V / 3180Ω
I = 72mA
This is the current available for the circuit.
LED Voltage Drop Calculation:
Each white LED has a forward voltage drop of approximately 3.2V.
8 LEDs in series = 8 * 3.2V = 25.6V
The arrangement has 3 such branches in parallel sharing the total current.
How to Build:
To build a Simple AC Mains Powered LED Night Light Circuit following steps are required to be followed:
- Assemble all he components mentioned in the above circuit diagram
- Connect one pin of bridge rectifier D1 to D4 to one end of resistor R1 and capacitor C1 in parallel and other end of resistor and capacitor connect to 230V AC
- Connect second pin of bridge rectifier to resistor R3
- Connect 3 pin of bridge rectifier to 230V AC through resistor R2
- Connect the fourth pin of bridge rectifier to negative of capacitor C2 and positive of capacitor connect to one end of resistor R3
- Connect from positive of capacitor C2 24 white LEDs anode of the LEDs to positive side and cathode of LEDs to negative to GND of the circuit.
Conclusion:
This Simple AC Mains Powered LED Night Light Circuit does not use a transformer which makes it a smart and energy saving way to power LEDs straight from the main AC supply.
It is perfect for things like night lights and decorative lighting.
Plus, without the heavy transformers the circuit is lighter and cheaper to make.
References:
How does this circuit, from an LED night light, work? [duplicate]