design and implementation of digital multimeter using arduino

Using Arduino Project Guidance
1

Hey guys! i am making a project about digital multimeter using arduino but i need your help about this project how much voltage and current values arduino will lead from analog read and how i cna make this multimeter in easy way.

thanks!

2

for that firstly i just want to know the full block and circuit diagram

your idea is important.

thanks!

3

I'd start here

4

Sounds not entirely dissimilar to the Ardutester. :smiley:

5

I'll try to get you started, but I recommend against it... I recommend that you DON'T try to build your own test & measurement instruments. If you need to do something specific, like monitoring the battery voltage in something you build, that's fine. But if you need a general-purpose multimeter, or oscilloscope, etc., I recommend you buy one.

how much voltage and current values arduino will lead from analog read

The maximum voltage on any Arduino pin is +5V. Anything higher, or a negative voltage can damage it.

You need a [u]protection circuit[/u] to protect against voltages greater than 5V and a to protect against negative voltages.

Then, to measure voltages greater than 5V, you need a [u]voltage divider[/u]. (In your meter you'll need multiple voltage dividers for multiple voltage-ranges.)

For measuring AC, you can use a full-wave rectifier for AC voltages above a few volts and then add-back the diode voltage drop in software. For lower voltages you can use a precision rectifier circuit (built with an op-amp). Then, you need to either calculate the true RMS voltage or read the peak and approximate RMS from the peak (which only works with sine waves). Or you can take a half-way approach, calculating the average and estimating RMS from the average.

Since the Arduino's inputs are very-high impedance, essentially zero current flows into the Arduino. Current is measured by inserting a known low-value resistor in series with the load, then measuring the voltage across the resistor and calculating current (from Ohm's Law). The resistance needs to be small to keep the voltage drop small, so it doesn't mess-up the circuit you are measuring.

Resistance is measured by passing a small-known current through the part/circuit, measuring the voltage, and calculating resistance (Ohm's Law again).[/b] The voltage & current need to be kept low do you don't fry sensitive low-power parts when you measure resistance.

6

@DVDdoug
You're right, the required components cannot be replaced by an Arduino. That's why I'd replace the Arduino by a DVM module with display, when I wanted to build my own multimeter nowadays.