• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

  • 1000+ Circuits
  • Privacy Policy
  • About Us
  • Contact
  • Disclaimer
  • Videos – Circuit Test Results
You are here: Home / Sensors and Detectors / Make an LED AC Voltage Indicator Circuit

Make an LED AC Voltage Indicator Circuit

Last Updated on November 2, 2020 by Swagatam 4 Comments

The LED AC mains voltage level indicator is a circuit that can be used for displaying the instantaneous voltage level of any 220 V or 120 V mains home AC input, through a correspondingly rising and falling LED bar graph.

A simple construction and accurate result are the main features of this tiny circuit. Learn how to make ac voltage indicator from led in a most simple and easy to understand method.

Why Monitor AC Mains Voltage Level

The AC mains line that we get in our household electric socket outlets, may at times be full of dangerous fluctuations. These may either be in the form of a sudden high voltage or a low voltage.
Both the situations can be very “fatal” to our sophisticated electronic equipments like TVs, DVD players, refrigerators, computers etc to name a few.

A simple electronic part such as an LED can play an important role in displaying the condition of this AC mains voltage and warn us of a possible electrical hazard. Yeah, we will exactly learn how to make ac voltage indicator using leds through a construction of a little electronic circuit.

mains AC voltage monitor circuit

How to Construct the LED AC Voltage Indicator

It is completed through the following few easy steps:

In the procured general purpose board, with the help of the circuit schematic start inserting the transistors first in a straight line and solder their leads.

Similarly insert and solder the resistors, zener diodes, LEDs, capacitors, presets etc. in an organized manner and solder them with reference to the circuit diagram.

How to Test the Circuit?

The following testing details will furthermore help you to understand exactly how to make ac voltage indicator from led:

For testing the completed circuit board you will require a transformer with multiple voltage outputs. Connect the transformer to the AC mains; also connect the common secondary output of the transformer to the negative point of the circuit. Make an alligator clip/ wire assembly. Solder the wire end of the clip to 1N4007 diode input.

Now bite the clip to the 3 volt output of the transformer, adjust P1 so that the first LED just starts glowing. As above go on connecting the clip to 6, 7.5, 9 and 12 volts of the transformer and adjust the presets P2, P3, P4 andP5 so that the relevant LEDs just start to glow at the respective voltages. This completes the testing and the setting of the circuit.

Finally join the 6 volt transformer to the circuit and switch ON the power. You will find that LED 1, 2 and 3 are glowing brightly,

LED no.4 is glowing with less brightness while the last LED is completely OFF, indicating a safe level of AC mains voltage. Now in case the voltage exceeds a high level (above 260 volts) the last LED will start glowing brightly indicating a dangerous situation.

If the voltage drops to a dangerous level (below 160 V) LED 3 and may be LED 2 may cease to glow, again indicating a bad low voltage.

Parts Required

You will need the following mentioned parts for the project:
TRANSISTORS T1, 2, 3, 4, 5 = BC547
ZENER DIODE Z1----Z5 = 3 VOLTS / 400mW
RESISTORS R 1—R10 = 1 K ¼ WATT, CFR.
CAPACITOR C1 = 1000uF/25v,
DIODE D1 = 1N4007
LED 1, 2, 3, 4, 5 = RED 5mm DIFFUSED
PRESET P1, 2, 3, 4, 5 = 47K LINEAR
GENERAL PURPOSE BOARD = 6” x 2”
TRANSFORMER = O – 6 VOLTS/ 500mA

Mains Voltage Monitor using LM358 IC

Knowing if the AC voltage level is on the low side by just looking is beneficial especially if you’re about to operate a computer.

But there is a hazard to this. Once the mains is already low, additional loads may force the AC voltage to plummet further beyond safety levels.

The supply for the current circuit is provided directly from the mains which happen across R1 and P1.

Two reference voltages are given by the 15 V steady-state voltage generated by R2, C1, C­2, D1 and D2.

Using a preset reference level of the mains voltage, these two voltages are compared in A1 and A2 from the IC LM358. If the subsequent mains become less than 210 V, D7 will illuminate. When the reading is more than 250 V, the light on D8 will be switched on.

If neither of them lights up, T1 turns on and allows D4 to be lit. This only means the mains voltage is in the safe operating limits.

How to Set Up

Preset P1 sets the AC voltage limit with help from the multimeter and a variac. You don’t need to strive for accuracy as any value around the centre of its travel is acceptable.

The circuit in the discussion is not isolated from the mains but must. We strongly urge you to verify that separated fiber case is always used to isolate this circuit from the mains before switching on.




Previous: How To Calculate and Connect LEDs in Series and Parallel
Next: 12V String LED Flasher Circuit

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

You'll also like:

  • 1.  LED Timer Indicator Circuit for Board Games
  • 2.  How Flex Resistors Work and how to Interface it with Arduino for Practical Implementation
  • 3.  Industrial Valve Switching Detector Indicator Circuit
  • 4.  Contactless Sensors – Infrared, Temperarture/Humidity, Capacitive, Light
  • 5.  3 Sound Activated Switch Circuits Explained
  • 6.  Automatic Light Sensitive Switch with Adjustable Dawn or Dusk Switching

Please Subscribe (Only if you are Genuinely Interested in our Newsletters)


 

Reader Interactions

Comments

    Your Comments are too Valuable! But please see that they are related to the above article, and are not off-topic! Cancel reply

    Your email address will not be published. Required fields are marked *

  1. Search Related Posts for Commenting

  2. 9707a392-a733-11e5-ac1d-d7e256602c6e says

    thanks a lot.
    I understand that.but what I mean is, to make the AC line automatically switching off from the appliance as soon as it detected the unsafe zone.
    greetings.

    Reply
    • Swagatam says

      OK, in that case one can try the following circuit

      https://homemade-circuits.com/2011/12/simple-mains-ac-over-voltage-and-under.html

      Reply
  3. 9707a392-a733-11e5-ac1d-d7e256602c6e says

    Good after noone Sir!
    Is it not good idia to develope this circuit in order to use more of it?I mean,as soon as voltage exceeds 260v and drops blew 160v,the AC line go to the "off" position.Is that not helpfull for the needy people who can not afford to buy voltage stabilizer?
    God bless you more and more for your nice work!

    Reply
    • Swagatam says

      thanks, below 160V and over 260V are unsafe zones so as soon as this is detected, the user can simply switch OFF the mains….so the above circuit definitely can be useful if used sensibly

      Reply


  4. COMMENT BOX IS MOVED AT THE TOP


Primary Sidebar

Electronic Projects Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (51)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (92)
  • 741 IC Circuits (18)
  • Amplifiers (49)
  • Arduino Engineering Projects (82)
  • Audio Projects (83)
  • Battery Chargers (75)
  • Car and Motorcycle (87)
  • Datasheets (44)
  • Decorative Lighting (Diwali, Christmas) (31)
  • DIY LED Projects (81)
  • Electronic Components (96)
  • Electronic Devices and Circuit Theory (34)
  • Electronics Tutorial (99)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Games (2)
  • GSM Projects (9)
  • Health Related (17)
  • Heater Controllers (23)
  • Home Electrical Circuits (98)
  • Incubator Related (6)
  • Industrial Electronics (25)
  • Infrared (IR) (39)
  • Inverter Circuits (94)
  • Laser Projects (10)
  • LM317/LM338 (21)
  • LM3915 IC (24)
  • Meters and Testers (52)
  • Mini Projects (152)
  • Motor Controller (64)
  • MPPT (7)
  • Oscillator Circuits (12)
  • PIR (Passive Infrared) (8)
  • Power Electronics (32)
  • Power Supply Circuits (64)
  • Radio Circuits (9)
  • Remote Control (46)
  • Security and Alarm (55)
  • Sensors and Detectors (115)
  • SG3525 IC (4)
  • Simple Circuits (72)
  • SMPS (30)
  • Solar Controllers (60)
  • Timer and Delay Relay (51)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (36)
  • Ultrasonic Projects (12)
  • Water Level Controller (45)

Follow Homemade Circuits

Facebook
Twitter
YouTube
Instagram
My Facebook-Page
Quora

Feeds

Post RSS
Comment RSS

Circuit Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator

© 2021 · Swagatam Innovations

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.Ok