LED light bulb

A power supply with a serial capacitor is used to power the LED. The current flowing through the LED is limited by the reactance of the capacitor. The connection is suitable for luminaires with a larger number of LEDs connected in series and a current of up to 50 mA. It can be used to implement luminaires up to a power input of several watts.

Circuit diagram:

led light bulb circuit

Losses occur in the circuit only on the protective resistor R1, the discharging resistor R2 and the rectifier diodes, the efficiency of the source is over 90%. Capacitor C2 should be 630 VDC, or you can use a 250 or 275 VAC suppression capacitor (usually labeled X2).

The table shows the current for different numbers of LEDs and for several capacitors of capacitor C2. Resistor R1 and capacitor C1 protect the LED from current pulses that can occur during sudden changes in supply voltage. C1 also reduces the ripple of the current flowing through the LED, but its effect on the mean current of the LED is small.

1 LED10 LED20 LED30 LED50 LED70 LED
C2 = 1000nF64 mA 57 mA47 mA42 mA32 mA20 mA
C2 = 680nF44 mA39 mA34 mA29 mA22 mA17 mA
C2 = 470nF30 mA27 mA24 mA20 mA15 mA
C2 = 330nF21 mA19 mA17 mA14 mA
C2 = 220nF14 mA13 mA11 mA
LED voltage3,5 V35 V70 V105 V165 V230 V

The module is designed to connect 10 LEDs in series. A current of 19 mA flows through the circuit.

Placement plan:

pcb placement led light

Printed circuit board:

pcb led bulb

Part list:
R11M
R2100R 2W
C1470uF/35V (voltage according to the number of LEDs)
C2330n/275VAC (in table)
M1graetz bridge round 1A
X1, X2screw terminal for PCB, RM=5mm, 2 pin
Real photo:
led light bulb circuitLED light circuit

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