I got AC voltage to display but now I need to read AC current

[xxrivera]

So I am doing a dc/ac converter and driving my mosfet drivers with arduino. So I am inputting 12vdc at the drives to make the h-bridge to go 12vac then I’m putting a step up transformer going from 12vac to 110ac. I then add a 15w light bulb as a load and I’m reading my values from the bulb.

I have got AC voltage at the output to read but now I want to make it read output current on the same LCD screen 16x2 with a button to have if and else statements.
I have used dmm and to read values but can’t use that since it’s my senior project need to use arduino

If (button_not_pushed) read voltage
if else (button_pushed ) read current.
I don't know how to implement it can someone help me pls !!!!!!!!

@engineerjtu

Hey Everyone,

#include <LiquidCrystal.h> // include Arduino LCD library

// LCD module connections (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);

void setup(void) {
lcd.begin(16, 2); // set up the LCD's number of columns and rows
lcd.setCursor(0, 0);
lcd.print("Output Voltage:");
analogReference(INTERNAL); // set ADC positive reference voltage to 1.1V (internal)
}

// get maximum reading value
uint16_t get_max() {
uint16_t max_v = 0;
for(uint8_t i = 0; i < 100; i++) {
uint16_t r = analogRead(A0); // read from analog channel 3 (A0)
if(max_v < r) max_v = r;
delayMicroseconds(200);
}
return max_v;
}

// main loop
void loop() {

char buf[10];
// get amplitude (maximum - or peak value)
uint32_t v = get_max();
// get actual voltage (ADC voltage reference = 1.1V)
v = v * 1100/1023;
// calculate the RMS value ( = peak/√2 )

v /= sqrt(2);

sprintf(buf, "%03u Volts RMS", v);
lcd.setCursor(0, 1);
lcd.print(buf);

delay(100);

}

Thank you

So, if the input voltage is 110V then the voltage across the 1k ohm resistor is 0.110V = 110mV (RMS values).

The 100nF ceramic capacitor is used to stabilize and eliminate noise of voltage signal across the 1k resistor. The 1N4733A Zener diode (reverse-breakdown voltage is 5.1V) is used to protect the Arduino board from voltages higher than 5.1V.
The following Arduino code measures the RMS value of the input AC voltage by detecting the maximum value of the half wave and then divide it by square root of 2 (√2).
So: Vrms = Vmax/√2

I need to build my own meter I cant buy it. My project will also be in a box and no wires will be exposed.

[build_1971]

You can add a current sensing resistor in series and measure the voltage over that resistor.
You may need an opamp to amplify the signal.
Another option is with a coil clamped around the wire.
If you are looking at mains AC, please forget about the resistor option!

[gilshultz]

Before commenting I would like to see an annotated schematic as to how this is connected.

[TomGeorge]

Hi, @xxrivera
Welcome to the forum.

https://forum.arduino.cc/t/how-to-get-the-best-out-of-this-forum

What voltages and currents are you measuring?

Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.

Thanks... Tom...

[horace]

have a look at CT sensors which clamp around one of the supply cables

[xxrivera]

They are Ac current and ac voltage
110 ac voltage
Max 2 amps current

[xxrivera]

You can look at schematic now I posted it

[xxrivera]

There

[anon94801460]

The circuit you posted for measuring AC voltage is extremely dangerous and totally unsafe.

You can find much better and safe options at the OpenEnergyMonitor web site.

[xxrivera]

Okay thanks I’ll look into it

[DVDdoug]

NOTE - IT'S DANGEROUS TO CONNECT DIRECTLY TO THE AC POWER LINE, even with the voltage divider (resistors) and a proper ground.

It would be illegal to sell a product like that unless it's completely enclosed in an insulated box with no outside connections (no USB connection and battery operated or powered from the same AC power line.)

If you build something like that, most of the development & testing should be done with safe voltages (12 or 24V) through an AC transformer whenever the USB is connected to your computer. Transformers are electrically isolated with no electrical connection between the primary and secondary... The energy is transferred magnetically.

...If I was building something like that, I'd use a transformer permanently, not just for testing & development. The secondary voltage is proportional to the primary voltage so it works just as well. (It is more expensive and bulkier).

A few months ago I was doing some "troubleshooting" and I needed to measure AC current. I bought a "Kill-A-Watt" meter. Notice how it's built-into a safe-plastic case?

I could have used my multimeter but this way I didn't have to mess-with wiring the meter in series. ...I'm not "afraid" of AC power and I wouldn't have bought it just for measuring voltage, but this was an easier and "cleaner" way of doing it. And now I have a new handy tool.

[xxrivera]

@DVDdoug @TomGeorge
I have added a few notes and other things on the original post

[xxrivera]

@gilshultz @anon94801460

[gilshultz]

??? Where ???

[TomGeorge]

@xxrivera

I have added a few notes and other things on the original post

PLEASE do not go back and edit earlier posts.
I makes the thread confusing to others who might want to use it to fix a problem they have.

PLEASE ANYMORE ADDITIONS IN NEW POSTS.

@DVDdoug

NOTE - IT'S DANGEROUS TO CONNECT DIRECTLY TO THE AC POWER LINE, even with the voltage divider (resistors) and a proper ground.

Very dangerous, in fact LEATHAL.

@DVDdoug

Transformers are electrically isolated with no electrical connection between the primary and secondary... The energy is transferred magnetically.

Can you please tell us your electronics, programming, arduino, hardware experience?

Tom...