Wednesday, May 4, 2011

LED Lighting For Consumer Unit Cupboard

The consumer unit (or ‘electricity meter’) cupboard in some older houses is a badly lit place. If the bell transformer is also located in this cupboard, it may be used to provide emergency lighting by two high-current LEDs. These diodes are powered via a small circuit that switches over to four NiCd batteries when the mains fails. The output voltage of the bell transformer is rectified by bridge B1 and buffered by capacitor C1. The batteries are charged continuously with a current of about 7.5 mA via diode D1 and resistor R2. The base of transistor T1 is high via R3, so that the transistor is cut off. When the mains voltage fails, C1 is discharged via R1; when the potential across it has dropped to a given value, the battery voltage switches on T1 via R3 and R1, provided switch S1 is closed. When T1 is on, a current of some 20 mA flows through diodes D4 and D5. The light from these LEDs is sufficient to enable the defect fuse or the tripped circuit breaker to be located.

Circuit diagram:
Author: H. Bonekamp

1 comment:

  1. led undercabinet lights Stunningly beautiful without glaring light. I really think this will be the wave of the future for lightening. Whatever the event, pay attention to the lightening and music and your event will be the talk of the town thank you for sharing this nice blog so keep it up