Hi am Anand i would like to get details on automatic low power emergency light project report free download pdf files ..My friend Justin said automatic low power emergency light project report free download pdf files will be available here and now i am living at ......... and i last studied in the college/school
Posts: 14,118
Threads: 61
Joined: Oct 2014
Here is an emergency light based on white LEDs that offers the following advantages. 1-It is very bright due to the use of white LEDs. 2-The light turns on automatically when the mains fails and shuts off when the mains resumes. 3-It has its own battery charger. When the battery is fully charged, the charge stops automatically. The charger power supply section is built around the LM317 (IC1) 3-pin adjustable regulator IC, while the LED driver section is built around the BD140 (Q2) transistor.
In the charger power supply section, a main AC input is reduced by T1 to deliver 9V, 500mA to the rectifier bridge, which comprises the diodes D1 to D4. The filter capacitor C1 removes the undulations. The unregulated direct voltage is supplied to input pin 3 of IC1 and provides load current through D5 and limiting resistor R15. By setting the P1 preset, the output voltage can be adjusted to supply the required load current. When the battery is charged to 6.8V, D6 leads and the charging current of IC1 finds a path through QT1 to ground and stops charging the battery. When the network is available, the base of Q2 remains high and Q2 does not conduct. Therefore, the LEDs are off.
On the other hand, when the network fails, the base of Q2 becomes low and leads. This makes all the LEDs glow. The mains power supply, when available, charges the battery and keeps the LEDs off while Q2 remains cut off. During the mains failure, the charging section stops working and the B1 supply causes the LEDs to glow. Mount the circuit in a general purpose PCB and lock in a cabinet with enough space for the battery and switches. We tested the circuit with twelve white 10mm LEDs. You can use more LEDs as long as the total current consumption does not exceed 1.5A. The excitation transistor Q2 can supply up to 1.5 A with a suitable heat sink arrangement.
![[Image: Automatic-Low-Power-Emergency-Light-1366...00_214.GIF]](https://d3i5bpxkxvwmz.cloudfront.net/resized/images/remote/http_s.eeweb.com/members/extreme_circuits/blog/2013/04/18/Automatic-Low-Power-Emergency-Light-1366340184_500_214.GIF)
Parts:
P1 = 2.2K
R1-R12 = 100R-1 / 2W
R13 = 1K-1 / 2W
R14 = 180R-1 / 2W
R15 = 16R / 5W
R16 = 1.2K
C1 = 1000uF-25V
D1-D5 = 1N4007
D6 = Zener of 6.8 V - 0.5 W
D7-D18 = 10mm- white LEDs
Q1 = BC548
Q2 = BD140
B1 = 6V-4.5Ah battery
IC1 = LM317
T1 = 9Vac-Transformer
