• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Need circuit help? Post them in the comments! I've answered over 50,000!

Blog | Categories | About | Contact | Calculators-online
You are here: Home / Lamps and Lights / IC 555 Automatic Emergency Light Circuit
warning message: electricity is dangerous, proceed with caution
simplestautomaticemergencylightcircuitusingIC555

IC 555 Automatic Emergency Light Circuit

Last Updated on January 2, 2024 by Swagatam 68 Comments

The discussed 2 simple IC 555 based emergency lamp system employs just a single IC 555 and yet is able to switch more than 20 LEDs directly, it will illuminate the LEDs only during the absence of mains power and ambient light.

Table of Contents
  • 1) Using IC 555 as a Comparator
  • Light Detection
  • 2) Using IC 555 Boost Converter
  • Using IC 555 as the Main Component
  • How L1 Functions

1) Using IC 555 as a Comparator

The proposed circuit is not only simple, it offers some very useful feature without involving too many components.

The use of IC 555 facilitates direct connection of the LEds across it's output pin#3, without needing an extra transistor driver buffer stage, although it may be incorporated in case more number LEDs are desired.

The IC is also configured as a light detector and furthermore a DC inverter.

Light Detection

The design has two features, 1) Mains outage detection, 2) Day night detection.

Whenever mains fails or in case of an outage, the lamp quickly detects this and automatically switches ON, to provide an emergency illumination in the premise

The light detection feature ensures that the IC switches ON the LEDs only in the absence of adequate ambient light.

The level of darkness or the level of ambient light at which the IC triggers the LEDs may be set by adjusting the value of R2. This is an added feature which allows customizing the triggering threshold.

The introduction of C1 offers yet another novel feature to the design, it offers some delay before the LEDs are switched ON once the above specified conditions are met.

That means C2 can be selected for getting certain time delay before the LEDs get switched ON.

Last but not the least, the IC also provides the facility which prevents the LEDs from illuminating for so long the AC mains stays active.

The reset pin of the IC is held at zero potential by the T1 during the presence of AC mains, the moment mains power fails T1 switches OFF connecting the reset pin#4 to battery positive, so that the IC is reset for the required triggering.

Just forgot to mention, the circuit also behaves like a trickle charger and keeps the associated battery fully charged and in a  standby condition whenever in need.

Caution: The circuit is not isolated from AC mains, so be extremely careful while testing.

Circuit Diagram

Parts List

R1 = 2M2
R2 = 1M
R3, R5 = 10K
R4, R6 = 120K
R7----R13 = 330 ohms
LDR = any standard type having ambient light resistance around 30K and  dark resistance to infinity.
D1---D4 = 1N4007
C1 = As required
C2 = 0.22uF/400V
T1 = BC547
LEDs = white, high efficiency, 5mm
Battery = 12V, 4AH

IC 555 Pinouts

LDR Image

image of LDR

2) Using IC 555 Boost Converter

The following emergency light circuit uses a very common voltage boost converter concept for making a group of white LEDs illuminate at relatively lower power supplies.

I have explained how to make this interesting and useful little LED boost emergency light circuit.

Yet again we take the help of the evergreen work horse, the IC555 for implementing the proposed actions.

boost converter circuit using IC 555

Using IC 555 as the Main Component

The figure shows a very simple circuit configuration where the IC 555 has been rigged as an astable multivibrator.

In an astable multivibrator design the various components are wired such that the output generates trains of pulses which are self sustaining and keeps coming as long as the circuit remains powered.

In the present configuration the output of the IC which is the pin #3 generates pulses at a frequency determined by the resistors R1 and R2 and also the capacitor C2.

R2 may be typically adjusted or made variable type for enabling dimming control of the LEDs.

However here the value of R2 has been fixed for acquiring optimum brightness from the LEDs.

The pulses available at pin#3 of the IC is used for ddriving the transistor T1 which in turn switches in response to the positive pulses.

The switching of the transistor pulls the supply voltage through the inductor in a pulsed mode.

As we know when alternating or pulsed voltage is applied across an inductor it tries to oppose the current and in the process kick an equivalent high voltage for compensating the applied current force.

This action of the inductor is what constitutes the boost action, where the voltage is stepped to higher levels than the actual supply voltage.

How L1 Functions

The above functioning of the inductor has been exploited in this circuit also.

L1 boosts the voltage in an attempt to restrict the applied AC, this high voltage generated across the coil during the non conducting phases of the transistor is fed across a series connected LEDs for illuminating them under lower current levels.

This process helps to illuminate the LEDs at relatively lower power consumption.

L1 winding is not so critical, it is a matter of little experimentation, the number of turns, wire guage, the diameter of the core, all are directly involved and affect the boost levels, therefore must be optimized carefully.

In the prototype I had used 50 turns of 22 SWG over an ordinary ferrite rod, which is normally used in small MW radio receivers.

The LEDs used by me were 1 watt, 350 mA types, however you may use different types if you want.

Parts List

R1 = 100K
R2 = 100k pot,
R3 = 100 Ohms,
R4 = 4k7, 1 watt
C1 = 680pF,
C2 = 0.01uF
C3 = 100uF/100V
L1 = see text
IC = LM555
T1 = TIP122
D1 = BA159

PLEASE CONNECT A 10 OHM RESISTOR IN SERIES WITH THE LED CHAIN FOR SAFEGUARDING IT FROM HIGH BOOSTED VOLTAGE.

INCREASING THE VALUE OF R2 SHOULD INCREASE THE BRIGHTNESS OF THE LEDs AND VICE VERSA.

You'll also like:

  • 1.  RGB Light Strip Controller Circuits
  • 2.  110V Compact LED Tubelight Circuit
  • 3.  Battery Over Charge Protected Emergency Lamp Circuit
  • 4.  Sound Triggered Halloween Eyes Project – “Don’t Wake the Devil”
  • 5.  4 Automatic Staircase Lamp Controller Circuits Explained
  • 6.  Automatic Night Activated Wireless Light Circuit for Paintings

Filed Under: Lamps and Lights Tagged With: 555, Automatic, Emergency, Light

About Swagatam

I am an electronics engineer and doing practical hands-on work from more than 15 years now. Building real circuits, testing them and also making PCB layouts by myself. I really love doing all these things like inventing something new, designing electronics and also helping other people like hobby guys who want to make their own cool circuits at home.

And that is the main reason why I started this website homemade-circuits.com, to share different types of circuit ideas..

If you are having any kind of doubt or question related to circuits then just write down your question in the comment box below, I am like always checking, so I guarantee I will reply you for sure!

Previous Post: « How Buck-Boost Circuits Work
Next Post: Simple Buck-Boost Converter Circuits Explained »
Subscribe
Notify of
guest
guest
68 Comments
Inline Feedbacks
View all comments

Primary Sidebar

circuit simulator image

Subscribe to get New Circuits in your Email

Categories

  • Arduino Projects (90)
  • Audio and Amplifier Projects (132)
  • Automation Projects (17)
  • Automobile Electronics (101)
  • Battery Charger Circuits (84)
  • Datasheets and Components (105)
  • Electronics Theory (140)
  • Free Energy (38)
  • Games and Sports Projects (11)
  • Grid and 3-Phase (19)
  • Health related Projects (25)
  • Home Electrical Circuits (12)
  • Indicator Circuits (15)
  • Inverter Circuits (89)
  • Lamps and Lights (142)
  • Meters and Testers (71)
  • Mini Projects (46)
  • Motor Controller (64)
  • Oscillator Circuits (28)
  • Pets and Pests (15)
  • Power Supply Circuits (89)
  • Remote Control Circuits (50)
  • Security and Alarm (64)
  • Sensors and Detectors (103)
  • SMPS and Converters (31)
  • Solar Controller Circuits (60)
  • Temperature Controllers (42)
  • Timer and Delay Relay (49)
  • Transmitter Circuits (29)
  • Voltage Control and Protection (38)
  • Water Controller (36)

Other Links

  • Privacy Policy
  • Cookie Policy
  • Disclaimer
  • Copyright
  • Videos
  • Sitemap

People also Search

555 Circuits | 741 Circuits | LM324 Circuits | LM338 Circuits | 4017 Circuits | Ultrasonic Projects | SMPS Projects | Christmas Projects | MOSFETs | Radio Circuits | Laser Circuits | PIR Projects |

Social Profiles

  • Twitter
  • YouTube
  • Instagram
  • Pinterest
  • My Facebook-Page
  • Quora
  • Stack Exchange
  • Linkedin
  • Recent Comments

    • Swagatam on Simple Buck Converter Circuits using Transistors
    • David on Simple Buck Converter Circuits using Transistors
    • Swagatam on Clap Switch Circuits with Relay ON/OFF: [Tested]
    • Mark on Clap Switch Circuits with Relay ON/OFF: [Tested]
    • Swagatam on Boost Converter Calculator

    © 2025 · Swagatam Innovations