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Mini Emergency Lamp



what is the battery ratings in ah?



what is the watts rating of the R1 - 100 ohm resistor.


U can take battery of ampere  4.5Ah or any heavy duty,and take 1/4watt of 1ooohm R

The voltage across a 1watt LED is 3.3v   The emitter-collector voltage-drop across the transistor is 0.2v   This gives 4.5v - 3.5v = 1 volt for the 10R resistor. The 10R resistor will only allow 100mA to flow - not the required 330mA.  The circuit has never been tested. 


well i have tested this circuit on circuit simulation its ok and working 

i am using nokia mobile charger as (ac to dc ) source

using 4v 500ma  sealed lead acid battery  

but the led is always on irrespective of ac source 

wel bd 140 is not working in this circuit .....

8550 did the job 




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