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DSO138 digital oscilloscope: assembly and setup instructions

 Turning on the DSO138 digital oscilloscope for the first time

The DSO138 digital oscilloscope is sold as a DIY kit. It is housed on one printed circuit board, and a TFT LCD display is connected to it with a separate mezzanine board. The oscilloscope is compact, very inexpensive and at the same time of sufficient quality. It has the function of storing the waveform, the function of displaying the parameters of the input signal, automatic, one-shot and normal operation modes. The bandwidth is 200 kHz. Voltage resolution - 12 bits. Let's see how to assemble this oscilloscope correctly and quickly.

DSO138 digital oscilloscope assembly and setup instruction

We need:

1Installation and soldering

The DSO138 set is on sale in this form ( you can buy it here ). The kit includes a printed circuit board itself with SMD components installed on it (there is also a type of kit where SMD components are not installed), a board with an LCD display, a bag with accessories, a cable with a BNC connector and "crocodiles", as well as assembly instructions and instructions on setting in English.

DIY kit DSO138
DIY kit DSO138

Having unpacked the kit, we proceed to the installation of radioelements on the printed circuit board. We will move strictly according to the instructions and observe the soldering sequence suggested by the manufacturer. For ease of assembly of the oscilloscope, the lowest components must be soldered first, then the highest.

The first step is to solder the resistors. There are many of them here, and many denominations. Soldering is carried out in the usual way: you mold the leads, insert into the holes, cover with flux, heat up, solder. Be careful and careful when soldering.

Installation of resistors on the DSO138 digital oscilloscope board
Installation of resistors on the DSO138 digital oscilloscope board

The next step is to solder three chokes and two diodes. The chokes are the same, but the diodes are different, but in the same housings. In addition, the diodes are polarized. On the silk-screen printing of the board, the "minus" (cathode) is indicated by a white line, as well as on the body of the diodes themselves. So be careful.

Installation of chokes and diodes on the DSO138 digital oscilloscope board
Installation of chokes and diodes on the DSO138 digital oscilloscope board

Next, we solder the 8 MHz quartz resonator. The polarity is not important.

Mounting a quartz resonator on the DSO138 digital oscilloscope board
Mounting a quartz resonator on the DSO138 digital oscilloscope board

Next, we solder the mini-USB connector to the board and five clock buttons. Both the connector and the buttons have specific dimensions of the case and pins, so it is impossible to confuse anything.

Mounting the USB connector and clock buttons on the DSO138 digital oscilloscope board
Mounting the USB connector and clock buttons on the DSO138 digital oscilloscope board

Next, we have to solder the capacitors. There are many of them, and there are many denominations. They are all non-polar and can be easily soldered. Remember to re-shape the leads before inserting the legs into the solder holes.

Mounting capacitors on the DSO138 digital oscilloscope board
Mounting capacitors on the DSO138 digital oscilloscope board

The next step is to solder the LED. The long lead is the anode, plus. A hole with a square contact pad is intended for it.

Mounting the LED on the DSO138 digital oscilloscope board
Mounting the LED on the DSO138 digital oscilloscope board

Now it's the turn of the white male power connector. We put it with its open part in the direction from the center of the board.

Installation of the power connector on the DSO138 digital oscilloscope board
Installation of the power connector on the DSO138 digital oscilloscope board

We install 2 transistors and 2 voltage regulators on the board. They are all different types, but in the same housings. Be careful when installing them on the oscilloscope board. Form the leads before installation and do not overheat them with a soldering iron.

Installation of transistors and voltage regulators on the DSO138 digital oscilloscope board
Installation of transistors and voltage regulators on the DSO138 digital oscilloscope board

We install two variable capacitors.

Installation of variable capacitances on the DSO138 digital oscilloscope board
Installation of variable capacitances on the DSO138 digital oscilloscope board

We mount a large inductor for the power supply filter.

Mounting the inductor on the DSO138 digital oscilloscope board
Mounting the inductor on the DSO138 digital oscilloscope board

Next, install 6 electrolytic capacitors. It is important to observe the polarity during installation. The longer output is a plus. It fits into a hole with a square solder pad.

Installation of electrolytic capacitors on the DSO138 digital oscilloscope board
Installation of electrolytic capacitors on the DSO138 digital oscilloscope board

We put a power connector on the DSO138 oscilloscope board. It has wide rather thick leads, it needs to be well soldered.

Installation of the power connector on the DSO138 digital oscilloscope board
Installation of the power connector on the DSO138 digital oscilloscope board

Next - soldering the pin headers and the corresponding pads to the DSO138 oscilloscope board.

Mounting pin headers on the DSO138 digital oscilloscope board
Mounting pin headers on the DSO138 digital oscilloscope board

Install three movable switches SW1, SW2 and SW3 . Then we mount the BNC connector. Its body is made of a thick layer of metal, and is difficult to solder. However, you need to solder it very well to the pads. This connector will often be subjected to mechanical stress and must be soldered very well.power up the thick leads of its case well.

Mounting the BNC connector on the DSO138 digital oscilloscope board
Mounting the BNC connector on the DSO138 digital oscilloscope board

Now we solder a loop of 0.5 mm wire into the holes of the J2 connector . This will be the pin for the oscilloscope's self-test signal output.

After that, short-circuit the JP3 jumper contacts with a soldering iron and solder .

Making a loop on the DSO138 oscilloscope board
Making a self-test loop on the DSO138 digital oscilloscope board

Let's deal with the TFT LCD screen board. You need to solder the 3 pin headers from the bottom of the board. Two small connectors with two pins and one double row 40-pin.

We are almost done with the soldering. But do not rush to remove the soldering iron, we will need it for a while.

Installation of connectors on the LCD screen of the DSO138 digital oscilloscope
Installation of connectors on the LCD screen of the DSO138 digital oscilloscope

Now it is advisable to rinse the board with acetone, gasoline or in some other way to clean it from traces of flux.

The washed board should be allowed to dry well. It is very important! No moisture should remain on the board at all.

After that, connect the power supply to the board and measure the voltage between ground and point TP22 .If the voltage is about 3.3 volts, then you soldered everything well, congratulations!Now you need to turn off the power supply and short-circuit the JP4 jumper contacts with solder .

We measure the voltage at point TP22 of the digital oscilloscope DSO138
We measure the voltage at point TP22 of the digital oscilloscope DSO138

Now you can connect an LCD display to the oscilloscope by aligning its pins with the pads on the oscilloscope's printed circuit board.

Turning on the DSO138 digital oscilloscope for the first time
Turning on the DSO138 digital oscilloscope for the first time

2First turn of theoscilloscope DSO138

Connect the power supply to the oscilloscope. The display should light up and the LED should blink twice. Then the manufacturer's logo and boot information will appear on the screen for a couple of seconds. After that, the oscilloscope will enter the operating mode.

Connect the probe to the oscilloscope's BNC connector and perform the first test. Without connecting the black lead of the probe, touch the red lead with your hand. A pick-up signal from your hand should appear on the oscillogram.

DSO138 Digital Oscilloscope First Test - Hand Touch
DSO138 Digital Oscilloscope First Test - Hand Touch

3Calibration of the oscilloscope DSO138

Now let's calibrate the oscilloscope. Connect the red probe to the self-test signal loop and leave the black unconnected. Set the SEN1 switch to the "0.1V" position, SEN2 to the "X5" position, and the CPL to the "AC" or "DC" position. Use the tact key SEL to move the cursor to the time stamp, and use the and set the time to "0.2ms" as shown in the illustration. A beautiful meander should be visible on the oscillogram. If the edges of the pulses are rounded or have sharp sharp peaks at the edges, it is necessary, by turning the capacitor C4 with a screwdriver , to ensure that the signal pulses become as close to rectangular as possible.

Calibration of DSO138 digital oscilloscope
Calibration of DSO138 digital oscilloscope

Now we put the SEN1 switch in the "1V" position, SEN2 - in the "X1" position. Leave the rest of the settings the same. Similar to the previous point, if the signal is far from rectangular, then we correct it by adjusting the capacitor C6 .

Calibration of DSO138 digital oscilloscope
Calibration of DSO138 digital oscilloscope

This completes the setup of the DSO138 oscilloscope. Let's test it out in combat. Connect the oscilloscope probes to a working electrical circuit and see the signal.

Oscilloscope DSO138 in operation
Oscilloscope DSO138 in operation

4Modes of operationoscilloscope DSO138

Possible modes of operation of the oscilloscope:

  • automatic (AUTO),
  • normal (NORMAL),
  • single (SINGLE).

Auto mode continuously outputs a signal to the oscilloscope screen. In normal mode, a signal is output every time the threshold set by the trigger is exceeded. One shot mode outputs a signal the first time the trigger is fired.

5Control elementsoscilloscope DSO138

Switches SEL1 and SEL2 are used to control the sensitivity of the oscilloscope . The first one sets the base voltage level, the second one sets the multiplier. For example, if you set the switches to the positions "0.1V" and "X5", the resolution of the vertical scale will be 0.5 volts per cell.

The SEL button navigates through the screen elements that you can customize. The setting of the highlighted element is carried out using the buttons and ... Items for customization are:

  • sweep time,
  • operating mode,
  • trigger edge selection,
  • response threshold,
  • movement along the horizontal axis of the oscillogram,
  • moving the axis vertically.

The RESET button resets and reboots the digital oscilloscope.

The OK button allows you to stop the sweep and hold the current waveform on the screen.

6Additional functionsoscilloscope DSO138

A useful function of the DSO138 oscilloscope is to display information about the signal: frequency, period, duty cycle, peak-to-peak, average voltage, etc. To activate it, move the cursor with the SEL button to select the sweep time, and then press and hold the OK button for 2 seconds .

Displaying information about the signal on the screen of the DSO138 oscilloscope
Displaying information about the signal on the screen of the DSO138 oscilloscope

The oscilloscope can memorize the current waveform in nonvolatile memory. To do this, press SEL and... To recall the stored waveform, press SEL and...

7Specificationsoscilloscope DSO138

Technical data of the oscilloscope DSO138, taken from the official passport.



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