ARM DSO203 Nano V2 pocket DSO

An oscilloscope is a basic piece of equipment for most DIY guys and girls. Older models were bulky, heavy and expensive. Modern scopes are digital, lightweight and packed with options we never dreamed of. They also became a lot cheaper.

My bench scope is an Atten ADS-1102CAL. It’s a typical 2-channel 100 MHz DSO (Digital Storage Oscilloscope) which sells for around $260 on eBay. I must confess that I haven’t used all the state-of-the-art options the Atten offers, such as computer connectivity. In the end most measurements involve looking at waveforms, measuring voltages in circuits and (occasionally) making use of FFT (Fast Fourier Transform).


Fast Fourier Transform
Yes, many of today’s digital oscilloscopes include FFT capability for frequency-domain analysis. This feature is especially valuable for oscilloscope users who have limited or no access to a spectrum analyzer, yet occasionally require frequency-domain analysis capability. Although a spectrum analyzer offers a much wider frequency range, exhibits better dynamic range and less distortion, the digital oscilloscope FFT provides a cost-effective, space-saving alternative.

Small, smaller, smallest
Then I ran into an ad for the ARM DSO203 Nano V2 / Quad Portable, a  pocket Digital Storage Oscilloscope. What? a 4-channel 72 MHz DSO for $165? Includes a waveform generator too? Can’t be right. Can’t work. Yet it does according to owners, and it’s based on open source.

ARM DSO203 Nano V2ARM DSO203 Nano V2 SizeARM DSO203 Nano V2 Inside

Analog channel x 2 : [CH_A] [CH_B];
Digital channel x 2 : [CH_C] [CH_D];
Vertical Scale: 20mV-10V/div (x1 probe);
Vertical solution: 8 bit ;
Input coupling: AC/DC ;
Max input voltage: 80Vpp (x1 probe);
Storage: 4K per channel
Software trigger type: edge, pulse, level (to be added)
Hardware trigger type: edge
Trigger source: CH1/CH2/EXT
Test Signal generator: 10Hz to 1Mhz
Storage: internal 2MB USB disk
Auto measure: Vmax, Vmin, Vpp, Vavr, Vrms, Freq, Period, Pulse, Duty
Cursor measurement: Level, Voltage
Display mode: CH1, CH2, EXT, CH1+CH2, CH1-CH2, CH1*CH2
Sampling mode: real time
Sampling rate: 1kSa/s – 72MSa/S
Power: Li battery
The color: Black
Dimension: 98 * 60 * 14.5
Weight: 80g (without battery)
Included accessories: 2 x Mueller mcx oscilloscope probe

OK, this gadget can’t match the bench scopes, there’s no FFT, but who knows what future firmware upgrades will bring us? Still, this DSO could be a nice addition to my ‘on the road’ kit, or be someone else’s first scope. Seen on eBay (link)

My 5-in-1 digital multimeter

A while ago I promised to shed some light on the test equipment I use. Some of it is complex (DSO, spectrum analyzer), some of it basic, like the multimeter described below. This one actually isn’t really basic at all, it has a lot of tricks up its sleeve. I used this sturdy little thing to measure lux when installing LED lighting, heat sink temperatures, audio frequencies, sound levels, and much more. Accuracy? No complaints whatsoever.

The price is around $50 when you include shipping. Hard to beat. You can find these on eBay. Factory specs below (copy & paste stuff):


This 5-in-1 Digital Multimeter is capable to measure direct- and alternate voltage, direct- and alternate current, capacitance, frequency, diode- and continuity test, duty cycle, temperature (°C), humidity (RH), illuminance (LUX) and sound level (dB). It has 14 functions and 39 measuring ranges that incorporates 5 devices — multimeter, sound Level meter, luxmeter, thermometer and hygrometer. Moreover, this multimeter received an iF product design award in Hannover with its cutting-edge design and outstanding functionality.

Features like Data Hold, Over range protection, Backlight LCD display and Auto Power Off have been added to this meter’s functionality making it ideal tool in schools, laboratories, industries and even in home applications.


  • All in Meter: Multimeter, Sound Level Meter, Luxmeter, Thermometer and Hygrometer
  • Performs DC & AC Current and Voltage, Resistance, Diode and Continuity Test, Capacitance and Frequency Measurements
  • Measures Sound Level (dB), Illuminance (Lux), Temperature (°C) and Relative Humidity (RH)
  • 14 functions with 39 auto and manual ranges
  • Over range protection for all ranges
  • Large LCD display with backlight
  • Data hold, low power indication, auto power off
  • Double Insulation

 Electrical Specifications

DC Voltage
Overload Protection
400 mV 0.1 mV ±(0.7% of reading + 2 digits) 250V DC or 250V rms AC
4 V 1 mV 600V DC or 600V rms AC
40 V 10 mV
400 V 100 mV
600 V 1 V ±(1.0% of reading + 2 digits)  
Input Impedance:  10MΩ/V
Maximum input voltage: 600V DC or 600V RMS AC

AC Voltage
Overload Protection
4 V 1 mV ±(0.8% of reading + 3 digits) 600V DC or 600V rms AC
40 V 10 mV
400 V 100 mV
600 V 1 V ±(1.5% of reading + 5 digits)  
Input Impedance:  10 MΩ/V
Maximum input voltage: 600V DC or 600V RMS AC

 DC Current

40 mA 10 µA ±(1.2% of reading + 3 digits)
400 mA 100 µA
10 A 10 mA ±(2.0% of reading + 10 digits)

Maximum Input Current: mA Jack: 400mA

**************************** 10A Jack: 10A
  AC Current
40 mA 10 µA ±(1.5% of reading + 5 digits)
400 mA 100 µA
10 A 10 mA ±(3.0% of reading + 10 digit
Maximum Input Current: mA Jack: 400mA, 
**************************** 10A Jack: 10A
Frequency (10 Hz ~ 1 MHz)
9.999 Hz 0.001 Hz ±(2.0% of reading + 5 digits)
99.99 Hz 0.01 Hz ±(1.5% of reading + 5 digits)
999.9 Hz 0.1 Hz
9.999 kHz 1 Hz
99.99 kHz 10 Hz ±(2.0% of reading + 5 digits)
199.99 kHz 100 Hz
> 200 kHz   Take it only as reference
– By Hz Range:
****Measurement Range: 0 ~ 200kHz
****Input Voltage Range: 0.5V – 10V rms AC (Input voltage must be enlarged
**** **** **** **** with increasing frequency under measurement)
****Overload Protection: 250V DC or rms AC
– By V Range:
****Measurement Range: 0 ~ 40kHz
****Input Voltage Range: 0.5V – 600V rms AC (Input voltage must be enlarged
**** **** **** ****with increasing frequency under measurement)
****Input Impedance: 10MΩ
****Max. Input Voltage: 600V DC or rms AC
– By mA Range:
****Measurement Range: 0 ~ 40kHz
****Input Current Range: 100mA – 400mA rms AC (Input
****Current must be enlarged with increasing frequency under measurement)
****Max. Input Current: 400mA DC or rms AC
****Overload Protection: F 500mA/250V fuse (quick acting).



0.1 Ω

±(1.2% of reading + 2 digits)

4 kΩ

1 Ω

40 kΩ

10 Ω

400 kV

100 O

4 MΩ

1 kΩ

40 MΩ

10 kΩ

±(2.0% of reading + 5 digits)

Open Circuit Voltage: 0.25V
Overload Protection: 250V DC or RMS AC

Diode Test
Diode 1 mV Display: read approximate forward voltage of diode

Forward DC current approximate 1 mA
Reversed DC Voltage approximate 1.5V
Overload protection: 250V DC or rms AC

 Continuity Check (Manual and Auto-Scan Mode)
Test Condition
600 Ω 0.1 Ω open circuit voltage: approx 0.5V

The buzzer will sound if resistance is lower than 40Ω


-20 ~ 0°C


±(5.0% of reading + 3°C)

0 ~ 20°C

±(3.0% of reading + 3°C)

20 ~ 400°C

±(2.0% of reading + 3°C)

-20 ~ 0°C


±(5.0% of reading + 5 digits)

0 ~ 400°C

±(1.0% of reading + 3 digits)

400 ~ 1000°C

±(2.0% of reading + 3 digits)

Overload Protection: F 500mA / 250V fuse (quick acting)


4 nF

1 pF

±(3.0% of reading + 3 digits)

40 nF

10 pF

400 nF

0.1 nF

4 µF

1 nF

40 µF

10 nF

200 µF

100 nF

±(8.0% of reading + 10 digits)

Overload Protection: 250V DC or rms AC

Duty Cycle

0.1 ~ 99.9%



Relative Humidity (RH)

30 ~ 90%


±5.0% RH

Operating Temperature: 0 ~ 40°C
Responding Time: 45% R.H.
90% R.H. = 10 minutes
************* ********90% R.H. 45% R.H. = 15 minutes


Sound Level (dB)

35 ~ 100 dB

0.1 dB

±3.5 dB at 94 dB, 1 kHz sine wave

Typical Instrument Frequency Range: 100 ~ 10000 Hz

Illuminance (Lux)

Lux (4000)

1 Lux

(5.0 % of reading + 10 digits) at color temperature 2850K calibrated to standard incandescent lamp at color temperature 2856K

x 10 Lux
x (40000)

10 Lux

– Repeatability : ±2%

  • Auto and manual range
  • 14 functions with 39 ranges
  • Maximum shown value: 3999 counts max
  • Over range protection for all ranges
  • Maximum Voltage between Terminals and Earth Ground: 600V DC or rms AC
  • Operating Altitude: 2000 Meters (7000 feet) maximum
  • Polarity indication: “-” indicates negative polarity
  • Over range indication: Display ‘0L’ or ‘-0L’
  • Sample Time: approximately 0.4 second
  • Unit showing: showing of function and electrical capacity
  • Auto power off time: 15 minutes
  • Fuse Protection: F 500mA / 250V (quick acting)
  • Low battery indication
  • Temperature Factor: < 0.1 x Accuracy / °C
  • Operating Temperature: 0 ~ 40°C (32 ~ 104°F)
  • Storage Temperature: -10 ~ 50°C (14 ~ 122°F)
  • Power Supply: 9 V PP3 Battery (included)
  • Dimension: approx. 178 x 85 x 40mm (L x W x H)
  • Weight: approx. 320g (batteries included)

Set Includes

  • 1 x 5-in-1 Multimeter
  • 1 Test Leads set
  • 1 x K-Type Thermocouple
  • 1 x 9V PP3 Battery
  • 1 x Instruction Manual
  • Standard Factory Package