Many electronics circuits and projects for learning in simple ways.

Simple AC mains voltage indicator circuit with LED

We have many ways to indicates an AC line. First, when 230VAC is provided, the neon-lamp assemble L1 light up. Another way, the AC mains voltage indicator circuit with a LED. It may be the best choice. If you have more normal components in your store. It helps you save money.

I also like to use the LED for display the power AC line. Because it is cheap and convenient with a few components only.

Single LED on AC mains
Simple AC mains voltage indicator circuit with LED


Simplest AC mains voltage indicator circuit diagram

How to connect LED to 230V AC voltage.

We know well that LED uses about 2V at 10mA only. When taking it to AC 230V. It requires reducing voltage and changing to DCV. For the first time, we often use a resistor to reduce the current in the series. But it is not suitable for the high AC voltage. Why?

The voltage across the resistor is too high, about 227V. Then, the current flows through is 10mA, like this LED. So the power of the resistor is about 227V x 0.01A = 2.27W. It is too hot.

The capacitor C1 is key in the circuit. It does not spread the heat out. (In principle)

We know that when the capacitor works in AC voltage. It is similar to a resistor. The resistance of the capacitor is called that Capacitive Reactance, in symbol Xc.
I am really stressed to explain the function of xc with simple text. I will explain to you later.

The Xc has a relationship Between frequency and capacity. If high capacity will be high Xc in the same frequency, 50Hz of AC line.

The capacitor limits the current through the LED to a safe value.

The R1 is limiting resistor to reduce the current. Also, it is the short circuit protection looks similar to a fuse.

The C1 capacitor reduces the current. It works well. When used with AC power. And rarely have problems with heat.

The diode D1 protects LED1 from the negative high voltage or current spike. Although LED1 does not work in reverse bias voltage. But this high voltage may kill its.

Important! You have to choose the capacitor-C1 Capacitors must have a DC working voltage (WVDC) of at least about 630V.

Cautions! Since this circuit no an isolated transformer, so you are careful to direct connect with into circuit. It causes electrical shock to you. AC line is very dangerous. It can kill us. Better way use the tiny isolated transformer.

I hope you are happy with this AC line 220V light display or main voltage monitor.

This Post Has 22 Comments

  1. One Response to “LED Indicator for remote AC loads”

    Hi,

    How are you friend?

    I,m interesting with your LED indicator for remote AC load.can you tell me the LEd will lip up based on how many AC amp load?

    I confused the LED type in your project it’s normal DC LED? Can i replace the LED with AC Bulb?

    Thanks,

  2. Could you please contact me regarding this? I’m interested in this and also a DC equivalent but with the source a max of 80VDC.

  3. How do I power a simple indicator LED with a wide AC input range (250VAC max) and I also have another circuit with wide DC input range (80VDC max)?

  4. Chris the voltage drop across the LED is minuscule compared to the high voltages. Subtract 2(red and yellow LED’s are normally 2 volts) or 3 volts from the AC voltage and use V = IR to use about 4 ma. That’s a 33K resistor on 120 volts and 68K on 240.

    In the last circuit example, why are you rectifying 120 or 240 volts and sending it to the Load? Who needs that much DC voltage?

  5. PS: That’s with 1/2 watt resistors. More milliamps means more watts. 8 ma(.008 amps) would require one watt resistors.

  6. Mains indicator with LED

    Thanks for your circuit!!

    It works perfectly.

  7. Just read on another web page for a 220V AC LED cct .. have the LED and a reverse connected IN4003
    and instead on nay resistor just use a 0.22uF Ceramic capacitor.

    Have you tried this ?
    States it avoids problem of dissipating heat in a resistor.
    Take a look at:
    https://www.instructables.com/id/LED-on-AC-Mains/

  8. Been looking a bit more into this … In your diag you show the 4k7 1W resistor.
    You can simply leave that out … the capacitor is providing current limit.

    You mention resistor is there for current limit in the event of a short.
    A short where ? in capacitor ? if that is case LED would act as fuse.

    Have you calculated what current is flowing thru resistor in normal state ? ……..
    I am thinking of simply discarding that resistor ..

  9. 1 have added 60 led in one circuit please tell me how to connect with direct ac 210v to 240v plzz help me
    i want to fix in my aquarium….
    thanks

  10. for the Mains Voltage Indicator with a LED,can i use 2000V 223nF capacitor?

  11. Question for “Mains Voltage Indicator with a LED”. I wanted to add it in our refrigerator plug. We only power off our refrigerator at least once a month for 30 minutes.

    1.) Will the circuit conneceted to our refrigerator will actually survive for at least 1 year?

    2.) In C1 what is current depression

  12. Question for “Mains Voltage Indicator with a LED”. I wanted to add it in our refrigerator plug. We only power off our refrigerator at least once a month for 30 minutes.

    1.) Will the circuit conneceted to our refrigerator will actually survive for at least 1 year?

    2.) In C1 what is current depression in easy-to-understand explanation? Is that the only purpose in this circuit?

    3.) If circuit is connected directly to welding machine power plug (also as power indicator) will it survive for a whole day welding-heavy-usage used?

    Thank You,
    mia

  13. How can do for three phase supply. Can it located close to the national grid meter. Can switch be included

  14. To elucidate my question further. From the mains there are three lines. Sometimes one or two of the phases may not have electric supply and there may be a need to change to the line that has electric supply. How can I have 3 indicator lights close to the meter to help me identify the line with electricity and connect. I am afraid of shorting the three phases

  15. Thanks, pls I need response to my earlier requests

  16. Hi to all

    I need led bulb ckt from 230v to DC ckt nd it should be 10w with 45 to 50 LEDs nd max lighting required with IC Configuration. Kindly provided this information

    thanking you
    satykishore

  17. Dear Friends,
    I have a 3 led power indicators to indicate the 3 phases in my cabinets, i want to know how many AMPERE for the fuse what i need.

    Thanks

  18. Capacitor supplies Suppression???
    I know I am not the only one wondering.
    Also the warning about polarity of connections seems a bit odd.
    I’d like to know the failure mode so that I can gauge the safety of this circuit.
    In short with this sort of post, when legitimate questions remain unanswered, I’d recommend getting a professional opinion before proceding.

  19. Dear all, how many of you still do live???
    Because I read a lot of inexperienced questions,
    so I can imagine none of you know actually how dangerous is
    life mains voltages, single or tri-phase !!!!!
    A capacitor reacts as a frequency dependant resistor,
    in theory without heat dissipation: Xc=1/(2*pi*f*C).
    Ad if you don’t know how to use this formola,
    I’d rather advice stay of it, and do something safer,
    because you don’t know the heck what U’re doing.

    1. Hello Harry,
      Thanks for helping teach us. Your comment is so good. AC line is very dangerous. It can kill us. Better way use the tiny isolated transformer.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Close Menu