This Digital Multimeter/Oscilloscope help you to
measure:

1 - Volts
2 - Ohms
3 - Temperature
4 - The light (lx)
5 - Frequency
6 - Amplitude
7 - Oscilloscope included
8 - Sound Generator sine wave 0Hz - 20000Hz included(in version pro)
9 - Color code resistance calculator
10 - Save measuring data!!
11 - Added capacitance meter from 1nF to 10000 mF

It's easy to build you just need:

1 -A arduino uno or nano
2 - Bluetooth module(HC-05 or HC-06)
3 - Temperature sensor(TMP36)
4 - Some resistances.

And for Oscilloscope:

1 - A old headphones with 4 pins
2 - Capacitor from 0.1mF to 1mF.

Please watch video tutorial How to use oscilloscope:

https://youtu.be/ZwNe8yEjjxo

**For build the circuit follow this**

LINK FOR DOWNLOAD SCHEMATIC:

https://drive.google.com/open?id=1Uo87XzR-_bAbjXLRFStOrAjYylbDcmdO

LINK FOR DOWNLOAD ARDUINO SKETCH HERE:

https://drive.google.com/open?id=1KAzkAE6AnySRy9rDWoByY9ezjj0eyMFN

Councils to improve the precision:

1 - Check the voltage of 5v pin of arduino after connecting everything it is the reference voltage to measure ohms when connecting the bluetooth module the voltage drops a bit it can be in 4.8v put exact value in the arduino code

2 - The values ​​of the resistances must be precise

2 - You must weld all the connections to avoid parasitic resistances

Multimeter/Oscilloscope try it now!