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Automatic Staircase Light 2

Circuit Diagram
automatic_staircase_light_2
Components Required
  1. Resistors
    1. R1 (2 Mega ohms, 1/2W)
    2. R2 (820 Kilo ohms, 1/2W)
  2. Integrated circuit
    1. IC1(741)
  3. Relay
    1. RL1 (9V/ 300 ohms)
  4. Capacitor
    1. C1 (10 mfd / 16V)
  5. Miscellaneous
    1. Push to on switch (S1, S2)
    2. Bulb( 9V/ 40mA)
    3. PCB or Breadboard
    4. Battery 9V
    5. Flexible Wire
    6. Soldering rod etc..
Principle and Working

This is also a push-to-on, and auto-OFF circuit. User needs to push the button only ones : To turn the light on. The light will turn automatically OFF after some time, since the switching OFF mechanism is timer based. Also note that the "push to on" switch is used here, this should be momentarily pushed to turn the light on.

When the button is pushed, relay gets triggered and charges capacitor C1. After release, the capacitor starts discharging through resistor R1. Since the R1 is of large value, C1 takes some time to get discharge. After C1's discharge relays turns off automatically. Good thing about this circuit is that, the circuit doesn't consume any power when it is not being used. This saves energy and increases battery life.