Saturday, November 3, 2012

Mains Powered LED Lights

Mains powered single LED

A single LED can be illuminated by using a 100n or 220n capacitor with a rating of 400v
  • The power diode in the first diagram is designed to discharge the 220n during one half of the cycle so that the capacitor will charge during the other half-cycle and deliver energy to the LED. The 1k resistor limits the peak in-rush current when the circuit is first turned on and the main happens to be at a peak.    
  • Two LEDs can be driven from the same circuit as one LED will be illuminated during the first half cycle and the other LED will be driven during the second half of the cycle.

Mains Powered Multiple LED's

When 50 to 80 white LEDs are connected in series, a resistor can be used. For 50 white LEDs, use a 4k7 2watt resistor to provide 10mA average current.For 100 white LEDs, use a 2k2 1watt resistor to provide 10mA average current.

Figure 2

The above circuit can be modified with a bridge rectifier to provide DC input to LED. This will prevent from flickering or strobing. 

Mains light with 10 LED

The following circuit illuminates a column of 10 white LEDs. The 10u and 100 R prevents flicker.

1 comment:

  1. R3 in fig 1 should be 1K instead of 100 ohms. I will update the image shortly.