Many Simple LED AC mains voltage & current indicator circuits

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 LED. It may be the best choice. If you have more normal components in your store. It helps you save money.

AC Main indicator circuits

1# AC mains led indicator

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.

2# AC line indicator circuit

If you are looking for a LED display for show AC-line power. This is AC line LED indicator circuit, that is compatible with the AC main power is 115 VAC or 230 VAC. In the circuit diagram, there are 2 LEDs for showing 2 status. First, it shows AC Main or the power grid. Second, show load still hold the power or not. It is nice circuit idea because using a few parts and cheap.

Operation of circuit

AC line LED indicator circuit

It’s a simple circuit. So interesting to learn its working. It is the main indicator of power while not pressing the switch S1. When we feed the 110V-AC to the power cord. The electrical current is flowing through R1, D1, LED1. So makes LED1 light up to reflect the input of the power.

Then, when we press switch S1, the electric current will flow through R2, D2, LED2. It makes LED2 light up instead of LED1. At the same time, some parts of the current flow to bias B lead of Q1-transistor. So, it makes Q1 work to connect all current of LED1 to ground. Makes LED1 go off.

Fuction of components

  • R1,R3 limits the current through the LED1,LED2 to a safe value.
  • D1,D2 rectifier AC to DC to LED1,LED2
  • R2 reduce the preper current to bias Q1

What is more? Do you want to remote AC load?


3# Simple LED AC power indicator circuit

This is an LED Indicator for remote AC loads Circuit. At very cheap and use electronic parts a little. This circuit uses diode rectifier cheapness, Resistor and LED only. As a result, assemble the circuit shows flowing from AC current Source in load easily.

Although intended to design for applying to office implement with main electric, we may modify this idea goes to are usable with the level low voltage get not difficult, please.

LED Indicator for Remote AC Loads

Circuit diagram of LED Indicator for Remote AC Loads

From originally at we use the way checks the condition of AC power Load by a temple AC Voltage. But when using this Simple LED AC power indicator circuit. You can check the event can work by check AC current flow through the load.

This circuit easily in case of Load and control switch stay far from the stall shows. Because misfire stands an electric line from load again the group. This circuit easily uses electronic parts a little with being normal rectifier diode 4 pcs, Resistors 1 pcs and LED 1 pcs only.

It is, as a result, can know that have current change load get already although. This circuit will suit AC house electric but this idea still can go to is using that is high-class low voltage get. By make volt be down 1.5V always just.

4# Current Transformer AC Load LED Indicator

This is a simple current transformer AC load LED Indicator circuit. The LED will show AC current of load, that use the transformer and LED as based on the circuit.

Sometimes we need to detect the large AC current.  One way is to connect the LED with the resistors and the diode 1N4001 networks.  But its disadvantage is the voltage will drop across them too much.

current transformer AC load LED Indicator circuit

But the best way is using the current transformer. The advantage of this way is current that will check, can convert to a neat instrument. And, the transformer also helps to separate the current to be measured with a meter out.

Which are very useful in measuring high current or high voltage.

This transformer may use a normal transformer. Using the lower voltage coil connects to the high current. Then, the primary coil connects to the LED or the meter.

In choosing the transformer.

The maximum current of the secondary coil and a maximum current of the LED is determined as follows.

Example: The current detector is 0.6A. Thus the lower coil will tolerate this current size. Assuming that the maximum current for the measurement is 30 mA. So, should choose a transformer 220 volts is 12 volts. To get an accurate conversion ratio (600/30).

The voltage loss to drop across the coil of the transformer is very low. And leakage current across the coil of the transformer is very low and may abandon it.

Thus the voltage loss so as the LED voltage divided by the ratio of the transformer.

The secondary coil of the transformer has to connect to load at all times. So we have the four diodes as the bridge to show both positive and negative waveform. If no load the secondary coil will be normal coil.

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I love electronic circuit. I will collect a lot circuit electronic for teach my son and are useful for everyone.
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