The working principle of an emergency light.

Replies

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  Scorpion007

  In most of emergency lamp a relay circuit is used turn off or on the lamp.you can take idea from below link
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  rdx dude

  For working states of all these device, is that first when they are in normal power supply, the lamp does not work, but the battery starts charging...
• 

  Jeffrey Arulraj

  rdx dude

  For working states of all these device, is that first when they are in normal power supply, the lamp does not work, but the battery starts charging...

  I am assuming Normal Supply as the mains, How does switching occur with out a relay. It is not clear in your post . Why not explaining it for us
• 

  Ramani Aswath

  zaveri

  now, i want to know what are all the devices present and how exactly they function, in carrying out the above processes.

  It is an exclusive 'OR' circuit. This can be implemented in many ways, simplest being an electromagnetic relay powered by the mains. The normally open contacts are used to power the lamp with the mains supply when present. When the mains go off, the relay also goes off and the normally closed contacts switch on to the stand by power source.
  The relay can be a solid state one also.
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  ashwin sarangula

  #-Link-Snipped-# : sir, could you please explain how does a solar water heater works ?
• 

  Ramani Aswath

  Try this simple experiment. Take a black non-stick coated pan, put some water in it, cover with a glass lid or even a clear polythene sheet and keep in the sunlight. After half an hour check the temperature of the water. Sun in Hyderabad is quite hot even in December.
  What happens is that the IR radiation passes through the transparent cover, passes through the water (which also absorbs a bit of the IR), strikes the black bottom coating, which absorbs the IR converting it to heat that warms the water. The warm water also tries to radiate heat back to space. However, the transparent cover is opaque to the long wave length of the re-radiated energy, which is retained. In roof top flat plate collectors the water is contained inside copper tubes welded to the blackened absorber plate. A thermal syphon recirculates the water passively to an insulated storage tank from which the hot water is supplied throughout the house.
  
  You can go through the info here:
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• 

  ABCD ABCD

  The OP says that the Emergency Light is off during mains ON. They might cutdown the mains voltage to +5v DC, and use that DC Voltage to control the Emergency Light using Digital Gates(AND, NOR, NOT in this case). No circuit would have been used to control the charging of battery, since the power cut itself will stop the battery from charging. As said above, the other way is to use relays.
  
  This is a good question, but you get to know these kind of stuffs as years pass on. You could have realized the answer by yourself intuitively in a year or two (if you had not asked here).