High Bright LED Emergency Lamp
Description
Contributor:
D.Mohankumar Here is a High efficiency Emergency Lamp using High bright White LEDs. It automatically turns on when power fails and turns off when power resumes. It is powered by a 6 volt 4.5 Ah rechargeable battery which can power the LEDs for a long period.
The battery charger section comprises a 0-9 volt 500 mA step-down transformer, a full wave bridge rectifier (D1 through D4), a 470 uF (C1) smoothing capacitor and 7808 voltage regulator IC. IC1 provides regulated 8 volt DC for charging the battery.
High bright LED Emergency Lamp Circuit
LED driver circuit uses a medium power PNP transistor BD 140 which acts as an automatic switch. When the mains power is available, battery gets charging voltage and current through D5 and R1. At the same time, unregulated voltage from the bridge rectifier passes through R2 to the base of T1 to inhibit its conduction. So both the LEDs remain off. When the power fails, T1 forward biases and the LEDs turn ON. If the brightness of LEDs is low, use 22 ohms 1w resistor as R3 and R4.
Comments (4)
Hay Mr. Mohankukmar, I need
Hay Mr. Mohankukmar,
I need an emergency lamp circuit that operates automatically. I have a 12V SLA battery of my old UPS. Thanks in advance.
-Vinod Chandran.
Hello Sir, I dont get
Hello Sir,
I dont get the better brightness with conventional LEDs. So can you guide me some LED types with better brightness. Also i want to increase the number of LEDs used pls let me know how to achieve that.
Also i want to know that how much time it takes to fully charge the batter and how long it can be used when there is no power..
Thank you
A 1watt LED takes 300mA.
A 1watt LED takes 300mA. The voltage drop across a 100R when 300mA flows is 33v!! The 100R can only deliver 25mA.
What is pulling the base LOW when the power fails? Another untested circuit.
sir, can i use 4.5 volts
sir, can i use 4.5 volts batery in this circuit.
and i want this lamp charge by mobile charger.