How does a voltage regulator differ from a zener diode?

[Wrichik Basu]

Indeed, for voltage limiting on an input signal there is such use for a zener, but you have to be careful, because the actual work (dissipation) will be on a serial resistor, not on a zener. This kind of circuits should be very carefully designed, especially if you want to measure anything related to line voltage (somehow this thread has such feeling...)

Yes, I will measure AC voltage with Arduino, and I have taken care of what you have said. Thanks for mentioning.

 

[CWatters]

Messing with mains/line voltage can be dangerous. Can I suggest you use an isolating step down transformer and multiply up in the Arduino.

 

[sophiecentaur]

Zeners and Voltage regulator ICs. I can't find a mention of the fact that there are Series and Shunt voltage regulators. This is very relevant. A Zener acts as a shunt regulator as it sits across the load with a series resistor to the supply. It's cheap and cheerful but it requires the current supplied by the source to be significant at all times - even when the load is high resistance or off (you need a standing current in the diode in order to get the Zener volts). For anything other than a very 'light load' (such as when the Zener is used as a low power voltage reference inside a circuit) the regulator dissipates a lot of power.
Most Voltage Regulators are Series regulators because they only need to supply / take very little current in addition to the current that the load draws. No load power will mean little or no power dissipated in the regulator.

 

[Wrichik Basu]

Messing with mains/line voltage can be dangerous. Can I suggest you use an isolating step down transformer and multiply up in the Arduino.

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?

 

[CWatters]

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.

 

[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.