How does a voltage regulator differ from a zener diode?

[Wrichik Basu]

Line/mains voltage is too high to be connected directly to an Arduino. The ADC cannot measure voltages that high. Some sort of pre-scaler is required to bring the voltage into the range the Arduino can measure. Bit like setting the range dial on your multi meter.

One way is to use some sort of diode/resistor network to reduce the voltage but in the event of a fault the whole circuit could become "live" and dangerous.

Another method is to use a transformer to step down the mains voltage to something safer first (say 5 or 10v) then use a diode/resistor network to get it in range of the ADC. If the transformer is suitably insulated then it's very unlikely any part of your Arduino circuit could accidental become live.

To be honest... if you have to ask about necessary safety precautions such as these you probably shouldn't really be attempting it.

Forgive me, I should have given this link before:

https://circuitdigest.com/microcontroller-projects/arduino-ac-voltmeter

My circuit is based on this but with slight variations. I will use a full-wave rectifier and some different values for the voltage divider resistors, and also a capacitor to get only the peak voltage. But the basic is same.

 

[sophiecentaur]

Can you explain a bit on what you mean by "isolating" transformer? Before connecting anything to the Arduino, I shall check with my multimeter first. Is that what you mean by "isolating" transformer?

My immediate reaction to this question and the way you phrase it, is to tell you not to go near 'Mains' Voltages until you have a bit more experience. If you want to measure anything but low (around 12) voltages then you should use a DMM. Even then, you should be wearing your 'Mains Aware' hat!
Even people who are very experienced with low voltage equipment like audio amps and microprocessors will usually use an off the shelf power supply and trust the 12V or 5V that it gives you.
To hang a circuit that connects to an Arduino to the Mainsm, you need to have all appropriate components that are rated for mains use - it can be dodgy to use 'out of the drawer' diodes, resistors or capacitors etc.. That's what I mean by "experience".

 

[CWatters]

Forgive me, I should have given this link before:

https://circuitdigest.com/microcontroller-projects/arduino-ac-voltmeter

My circuit is based on this but with slight variations. I will use a full-wave rectifier and some different values for the voltage divider resistors, and also a capacitor to get only the peak voltage. But the basic is same.

And there in the picture is a transformer.

 

[anorlunda]

The original answer about zener diodes has been more than adequately answered.

Thread closed.