Last time we mounted all the radio elements on the printed circuit board of the DSO138 digital oscilloscope. Now we will finish assembling it and perform the initial configuration and performance check.
It is necessary
- - Set with digital oscilloscope DSO138;
- - multimeter;
- - power supply for 8-12 V;
- - tweezers;
- - screwdriver for small jobs;
- - soldering iron;
- - solder and flux;
- - acetone or gasoline.
Instructions
Step 1
First of all, we solder a loop of wire 0.5 mm thick 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.
Step 2
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're almost done building. But do not rush to remove the soldering iron, we will need it for a while.
Step 3
Now it is advisable to rinse the board with acetone, gasoline or in some other way to clean it from traces of flux. When we wash the board, you need to let it dry completely, this is very important!
After that, connect the power supply to the board and measure the voltage between ground and point TP22. If the voltage is approximately equal to 3.3 volts, then you have soldered everything well, congratulations! Now you need to turn off the power supply and short-circuit the JP4 jumper contacts with solder.
Step 4
Now you can connect an LCD display to the oscilloscope by aligning its pins with the pads on the oscilloscope's printed circuit board.
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.
Step 5
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.
Step 6
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 button SEL to move the cursor to the time stamp, and use the "+" and "-" buttons to 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, you need to turn the capacitor C4 with a screwdriver to ensure that the signal pulses become as close to rectangular as possible.
Step 7
Now we will 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.
Step 8
This completes the setup of the DSO138 oscilloscope. Let's put it to the test in combat.
Connect the oscilloscope probes to a working electrical circuit and see the signal.
Step 9
The SEL1 and SEL2 switches are used to control the sensitivity. The first one sets the base voltage level, the second one sets the multiplier. For example, if you set the switches to 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. Adjustment of the highlighted item is carried out using the + and - buttons. The elements for setting are: sweep time, trigger mode, trigger edge selection, trigger level, movement along the horizontal axis of the waveform, and vertical movement of the axis.
Supported operating modes: automatic, normal and one-shot. 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.
The OK button allows you to stop the sweep and hold the current waveform on the screen.
The RESET button resets and reboots the digital oscilloscope.
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, press and hold the OK button for 2 seconds.
The oscilloscope can memorize the current waveform in nonvolatile memory. To do this, press SEL and + at the same time. Press SEL and - to call up the stored waveform.
