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 thiscircuit 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 = 15KR2 = 1K5R3 = 22KR4 = 680 ohmR5 = 47 ohm Capacitors:C1 = 100uF/25V, electrolyticSemiconductors: Q1 = BC557B, general purpose PNP transistorD1-D3 = 1N4148 Leds = Ultra High Brightness, blue/white, 20.000 mCd or higherBR1 = B80C1000 (80V/1A) Bridge Rectifier Miscellaneous:S1 - Main Fuse panel door switch (optional), or regular on/off switch.4 NiCad batteries, 1.2V/750mAh
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.
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