In search for a cost-effective and portable scope that performs all the basic DSO functions? Make no mistake, the DSO138 digital oscilloscope is ready to do this job.
Introduction
A portable oscilloscope can be a handy tool for your busy and cluttered workspace. This device is lightweight and small, making it easy to place anywhere on your desk. Additionally, you may want all the usual functions of a standard DSO to come along with it, such as display measurements, one-shot triggers, capture waveform, and others. With this, you may want to check out the DSO138 Digital Oscilloscope w/acrylic case.
What's so special about this scope?
This scope, intended to be a DIY or assembled kit, has most of the features of a standard DSO, thanks to its powerful 32-bit microcontroller STM32F103C8. Below are its specifications:
DSO138 Specifications:​
| Microcontroller | ARM Cortex-M3 (STM32F103C8) |
| Analog Bandwidth | 0 - 200 kHz |
| Sampling Rate | 1 MSa/s |
| Sensitivity | 10 mV/Div - 5 V/Div |
| Vertical Resolution | 12-bit |
| Input Impedance | 1 MΩ |
| Maximum Input Voltage | 50 Vpk |
| Coupling | DC, AC, GND |
| Timebase | 10 µs/Div - 500 s/Div |
| Record Length | 1024 points |
| Display | 2.4-inch color TFT LCD (320 x 240) |
| Power Supply | 9V DC (8 - 12V acceptable) |
| Supply Current | 120 mA |
| Physical Dimensions | 117 mm x 76 mm x 15 mm |
| Weight | 70 g (excluding cables) |
The STM32F103C8 is an ARM Cortex-M3 MCU capable of up to 72MHz clock speed. Internally, it has 20KB of RAM and 64K bytes of flash. It has a 12-bit ADC capable of sampling up to 1M/s and can use a DMA controller. Overall, these specs are suitable for a modest mini-DSO intended for hobbyist’s needs.
DSO functions
Trigger Modes
Just like a regular DSO, the DS0138 can be triggered in three modes:
- Auto – Continuous waveform
- Normal – Trigerred on edge
- Single –Â One shot triggered
The trigger position is 1/2 of buffer size (fixed).
Waveform Measurement Function
You’ll be able to automatically display the measurements and timings of the waveforms with a press of a button. Press the hold function to do this. You can even see the measurements in real-time if you like.
SAVE/RECALL WaveformFfunction
You’ll be able to save or recall your captured waveforms, a function you cannot do using analog scopes.
Analog Front-End
The DSO138 has an analog front-end implemented through a TL084 quad operational JFET OP-AMP. With this, it’s possible to capture waveforms up to 50V max. JFET OP-AMPS are known to have good noise immunity, high-speed, high input impedance, wide operating voltage and rail-to-rail output.
Standard BNC to Alligator Type Probe
The unit has a standard BNC connector split into positive and negative alligator clip probes.
Internal Test Signal Function
You don’t have to worry about your measurements drifting away; this scope has a built-in test waveform function using a 3.3V 1KHz square wave.
Portable Power
You can power this scope from a single 9V DC source.
Open Firmware Solution
Additionally, you’ll have access to its firmware and source code. You can flash newer published versions or even modify the firmware if you want. The source library is readily available to download and is documented.
If you need to upgrade firmware, you only need to modify some jumper settings and have a USB-to-UART converter tool.
