Emergency Light. Home Utility Circuit 10

emergency-lightMake your own Emergency light using only a few components. It is powered by a 4 V 2 Ah Mini Lead Acid battery and uses Six 0.5 Watts White LED. Its output will be 3 Watts. Let us start to make it.

You need the following components
1. 6-0-6, 500 mA Transformer
2. IN 4007 Diodes – 3 Nos
3. 470 uf 25V Electrolytic capacitor – 1 No
4. 68 Ohms ½ watt resistor – 1No
5. 4.7K ½ watt resistor – 1No
6. 2.7K ¼ watt resistor – 1No
7. 4.7Ohms ½ resistors – 6 Nos
8. BD 140 PNP Transistor – 1No
9. 0.5W White LED – 6 Nos
10. 4V 2 Ah rechargeable Lead Acid battery – 1 No.

Working of the circuit is simple. When the mains power is available, D3 forward biases and battery charges through R1. At the same time, the base of NPN transistor T1 remains high through R2. So it will be off. When the mains power fails, D3 reverse biases and the current through R2 ceases. This makes the base of T1 low and it conducts. Current from the battery flows through T1 to light the White LEDs.

Resistors R4 to R9 restricts the LED current . 0.5 Watt White LED handles more than 100 mA current so you can change the value of R4-R9 according the brightness required. Lower value increases brightness and higher value decreases the brightness.

Add your Comments here and Click Post Comment. For Queries, come to the Discuss and Share Forum

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s