Multimeter/Oscilloscope

Turn your phone into a complete electronics workbench! Build a simple Arduino board, connect it by Bluetooth or USB, and read volts, current, resistance, capacitance, inductance and temperature right on your screen. Plus an oscilloscope, a signal generator and a resistor color code calculator that work without any extra hardware.

⚡ MULTIMETER (with your Arduino board)
• DC voltage (V)
• DC current (mA) – ammeter
• Resistance (Ω) with 3 ranges: 220 Ω, 10 kΩ and 100 kΩ
• Continuity test with beep
• Capacitance meter (nF)
• Inductance meter (µH)
• Temperature (°C)
• HOLD button to freeze a reading, just like a bench meter

📈 LIVE GRAPHS
• See every reading drawn in real time
• Zoom in and out, center on the value, drag to look back in time
• Pause the graph and scroll through the history
• Save graphs and open them later to study your measurements

💾 SAVE YOUR MEASUREMENTS
• Store any reading with one tap
• Add a name and description to each saved value
• Edit or delete your notes whenever you want

📟 OSCILLOSCOPE (no Arduino needed)
• Watch signals through your phone's audio input
• Peak-to-peak measurement
• Calibrate the input with a known signal for accurate voltages

🔊 SIGNAL / SOUND GENERATOR (no Arduino needed)
• Sine, square, triangle and sawtooth waves
• Frequency from 20 Hz to 20,000 Hz
• Adjustable duty cycle for square waves
• Adjustable amplitude

🎨 RESISTOR COLOR CODE CALCULATOR (no Arduino needed)
• 4, 5 and 6 band resistors
• Shows value, tolerance and temperature coefficient

🔌 EASY CONNECTION
• Bluetooth: HC-05 or HC-06 module – search, pair and connect inside the app
• USB cable: USB-serial adapters (CH340, FTDI, CP210x, PL2303) with an OTG cable

🔦 EXTRAS
• Built-in flashlight button to light up your circuit
• Portrait and landscape layouts
• Available in English, Spanish and Russian
• NO ADS!

🛠 EASY TO BUILD
You only need:
1. An Arduino Uno or Nano
2. A Bluetooth module (HC-05 or HC-06) or a USB-serial cable
3. A temperature sensor (TMP36)
4. A few resistors

For the oscilloscope:
1. Old headphones with a 4-pin jack
2. A capacitor from 0.1 µF to 1 µF

Schematic and Arduino sketch – free download:
https://neco-desarrollo.es/arduino-multimetro

Video tutorial – how to use the oscilloscope:
https://youtu.be/ZwNe8yEjjxo

🎯 TIPS FOR BETTER ACCURACY
1. Measure the real voltage on the Arduino 5V pin once everything is connected. It often drops to about 4.8 V. Write the exact value in the Arduino sketch – it is the reference for measuring resistance.
2. Use resistors with values as accurate as possible.
3. Solder all connections to avoid unwanted extra resistance.

Questions about building the circuit? Write to us – our e-mail is below. We are happy to help!

Website: https://www.neco-desarrollo.es

Perfect for students, makers, hobbyists and anyone who loves electronics. Build it, measure it, learn it!

Recent changes:
Bugs fixed.