Schematic Diagram

The area around the Main Electrical Panel is usual pretty dark, especially if it is located in the basement. That's during daylight hours. At night everything is dark during a powerfailure, or tripped circuit breaker, fuse, etc..
This circuit provides ample time to fix the problem.

A bell transformer is used to provide the AC power to the circuit. It can be anything from about 6 to 12VAC and this circuit can be used without modifications for this AC range. Just watch the working voltage of the electrolytic capacitor C1. A 25V type will work but to keep if safe go for a 50V or better.

When the main power is interrupted for any reason, the circuit is fed via the 4 NiCads which provide 750mAh at about 5 volt DC. The LED's are of the ultra-bright type, 20,000mCd or better.

Parts List:
Resistors are 1/4 Watt, 5%
R1 = 15K
R2 = 1K5
R3 = 22K
R4 = 680 ohm
R5 = 47 ohm
C1 = 100uF/25V, electrolytic

   Q1 = BC557B, general purpose PNP transistor
D1-D3 = 1N4148
 Leds = Ultra High Brightness, blue/white, 20.000 mCd or higher
  BR1 = B80C1000 (80V/1A) Bridge Rectifier	
S1 - Main Fuse panel door switch (optional), or regular on/off switch.
4 NiCad batteries, 1.2V/750mAh
Transistor Q1:
The BC557B can be replaced with a NTE159, but Rotate device 180 to conform with original lead configuration.

Copyright and Credits:
Source: "Elektuur, Halfgeleider Gids", 1998. Copyright © Elektuur Magazine, The Netherlands.
Document updates & modifications, all diagrams, Layout, editing, © Copyright by Tony van Roon.
Re-posting or taking graphics in any way or form of this project is expressly prohibited by international copyright laws.

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Copyright © 1995 -- Tony van Roon
Last updated June 19, 2006