Mini Digital Oscilloscope DIY Soldering Kit Assembly

Written By: Nick Schultz

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Mini Digital Oscilloscope DIY Soldering Kit Assembly

Difficulty

Very difficult

Steps

Time Required

2 - 4 hours

Introduction

Follow this guide to build a portable oscilloscope using the Mini Digital Oscilloscope DIY Soldering Kit. This kit is designed for individuals looking to advance their surface-mount soldering skills, and isn't suitable for beginners. If this is your first time soldering, we'd recommend starting with a beginner-friendly kit.

If you'd like to read up on soldering techniques before diving in, check out our guide on soldering and desoldering connections.

Tools

Parts

DIY Soldering Kit Mini Digital Oscilloscope

Step 1

If you're working indoors, place your fume extractor next to your project. Set up your tools in a well-lit area, away from anything flammable:
A pair of safety glasses (solder spatter will damage regular glasses)
A soldering iron and solder (leaded or lead-free)
A pair of angled tweezers
A tip cleaning tool (damp cellulose sponge or brass wool)
A pair of flush cutters
A desoldering pump and/or solder wick (aka desoldering braid), in case you make a mistake.
(Optional) A silicone work mat to prevent damage to your work surface.

Step 2

Your oscilloscope kit contains the following parts:
Circuit board
Case
Microcontroller (aka CPU)
Resistors & capacitors
Power inductor
External interfaces
OLED display and display connectors

Step 3

Each resistor and capacitor (besides the three 2 kΩ resistors) are unique, and must be installed in their correct spot on the board. The 10 μF and 22 nF capacitors look identical apart from the packaging labeled 103. Use tweezers to remove each component's packaging before soldering.
LED
1W/10 kΩ (103) resistor
10 kΩ (103) resistor
2 kΩ (202) resistors
10 μF capacitor
10 nF (103) capacitor
22 nF capacitor

Step 4

Set down the circuit board on your work mat/surface so the front (the side labeled MiNi-DSO at the top) is facing up.

Step 5

Put on your safety glasses.
Turn on your soldering iron. If your soldering iron has temperature control:
Set it to 300 °C (~570 °F) if you're using leaded solder
Set it to 375 °C (~700 °F) if you're using lead-free solder
Clean the tip of your soldering iron. If you're using a cellulose sponge, wet the sponge with distilled water until damp and quickly wipe the tip across it. If you're using brass wool, stab the tip into the wire a few times.
Melt a small glob of solder onto the tip of the iron. This is called "tinning the tip" and will help with heat transfer.
You'll likely see some wispy smoke as you melt solder. This is mostly the rosin-core flux that's built into the solder wire. Flux helps molten solder flow, but gets vaporized over time.

Step 6

In this step, you're going to pre-load one of the resistor's pads on the board with solder. This will make it easier to solder the resistor.
Press the iron's tip against one of the solder pads in the outline labeled R4 for a few seconds to heat it.
If you heat the circuit board continuously for more than 10 seconds, the excessive heat may damage the solder pad.
Feed the solder wire into the heated area until there's a small glob of solder on the pad.
The solder should melt onto the pad within a few seconds. If the solder doesn't adhere to the pad, apply flux to the pad or increase the temperature.
Remove the solder wire first, then remove the soldering iron from the pad.

Step 7

Place the largest 10 kΩ resistor (labeled 103) in the outline labeled R4 on the board.
For a handy surface-mount resistor value calculator, click here. All the resistors in this kit are 3 digit EIA (Electronic Industries Alliance).
Re-heat the solder while holding the resistor in its outline until the molten solder envelops the end (shiny) cap.
All the resistors through Step 13 are symmetrical and can be soldered in either orientation.
If the solder won't envelop the cap, add some flux or a little fresh solder and try again.
Remove the iron, then remove the tweezers once the solder has cooled.

Step 8

In this step, you're going to heat the solder pad and the resistor's end cap so that they'll readily melt the solder wire.
Press the tip against the second R4 solder pad and the resistor's second end cap for a few seconds to heat them both. Angle the tip so it has maximum contact with the pad and cap.
If you heat them continuously for more than 10 seconds, the excessive heat may damage the solder pad or resistor.
Feed the solder wire into the heated area until there's a small glob of solder surrounding the end cap.
Remove the solder wire first, then remove the soldering iron from the pad.

Step 9

Congratulations—you've soldered the resistor to the board!
If one of the solder joints doesn't make contact with an end cap, reheat the cap and add more solder. If the solder isn't flowing neatly, apply flux to the joint before adding more solder.
Check if any solder has unintentionally bridged with a different pad. If so, carefully use your iron to heat the solder between the pads and separate the bridge. If the bridge doesn't want to separate, desolder it and try again.

Step 10

Press the iron's tip against one of the board's R2 solder pads for a few seconds to heat it.
Feed the solder wire into the heated area until there's a small glob of solder on the pad.

Step 11

Place the smaller 10 kΩ resistor (labeled 103) in the outline labeled R2 on the board.
Press the soldering iron's tip onto the edge of the solder pad while holding the resistor in its outline, so that its end caps (the shiny parts) are resting on the circuit board's pads.
Remove the iron, then remove the tweezers once the solder has cooled.

Step 12

Press the tip against the second R2 solder pad and the resistor's second end cap for a few seconds to heat them both. Angle the tip so it has maximum contact with the pad and cap.
Feed the solder wire into the heated area until there's a small glob of solder surrounding the second end cap.

Step 13

Repeat this process to solder the three 2 kΩ resistors (labeled 202) in the outlines labeled R3, R1, and R5 on the front of the board.

Step 14

Repeat the process to solder the three capacitors to the front of the board:
The large capacitor in the outline labeled C1
The capacitor labeled 103 on its packaging in the outline labeled C2
The 22 nF capacitor (with no label on its packaging) in the outline labeled C3

Step 15

Press the iron's tip against the circuit board's LED solder pad for a few seconds to heat it, then feed the solder wire into the heated area until there's a small glob of solder on the pad.
Place the LED in the outline labeled LED on the board, with the white (non-green) side aligned with the "+" symbol.
The green markings indicate the negative (-) side.
Solder the LED's first end cap to the board.
The LED's contact pads are underneath it, so the solder joint doesn't need to cover the entire end.

Step 16

Press the tip against the second LED solder pad and feed the solder wire into the heated area until there's a small glob of solder contacting the end cap.
The LED's contact pads are underneath it, so the solder joint doesn't need to cover the entire end.
Remove the solder wire first, then remove the soldering iron from the pad.

Step 17

In this step, you're going to apply solder to one of the microcontroller pads to help with alignment when you solder it to the board.
Press the iron's tip against the board's bottom left microcontroller solder pad for a few seconds to heat it.
If you heat the circuit board continuously for more than 10 seconds, the excessive heat may damage the solder pad.
Feed the solder wire into the heated area until there's a small glob of solder on the pad.
Since these pads are so close together, it's easy for the solder to adhere to multiple pads. This is fine as long as the pads aren't bridged to each other.

Step 18

Repeat the last step to apply solder to the board's top right microcontroller solder pad.

Step 19

Orient the microcontroller with its outline (labeled U1) on the circuit board, so the circle on microcontroller is on top of the circle on the board.
The indented circle on the microcontroller should be facing the same corner as the dot next to the U1 label on the board.
Align all 44 pins are aligned with their respective pads on the board.
Ensure the microcontroller is aligned both vertically AND horizontally. Once multiple pads are soldered, it is extremely difficult to remove the microcontroller and try again.
Hold the microcontroller still with tweezers and re-heat the solder from the last two steps to solder it to the board.
If you have polyimide tape, you can use it to hold the microcontroller still while you solder the first two leads.

Step 20

This process is both difficult and time-consuming. Take your time and be extra careful not to overheat the solder pads or pins. Avoid using desoldering wick to desolder the leads, as it could easily destroy the pads.
Press the tip against another solder pad and feed the solder wire into the heated area until there's a small solder joint on the pin.
Check if any solder unintentionally bridged with a different joint. If so, carefully use your iron to heat the solder between the joints and separate the bridge. If the bridge doesn't want to separate, desolder it using a desoldering pump and try again. Be careful not to overheat the pins or the pads while desoldering.
Repeat this process for all of the remaining microcontroller pins.

Step 21

Align the USB port with the outline labeled USB on the front of the board.
Insert the leads of the USB port into their four holes on the board, so it sits flush.

Step 22

Flip the board over so the pins are facing up.
Press down with the tip of your iron on the one of the USB port's solder pads closest to the edge and solder the USB port's first pin.
Solder the remaining USB port pins.

Step 23

Align the UART connector with the outline labeled UART on the front of the board.
Insert the shorter pins of the UART connector into their four holes on the board, so it sits flush.

Step 24

Flip the board over so the pins are facing up.
Solder the UART connector to the board.

Step 25

Press the iron's tip against the circuit board's L1 solder pad for a few seconds to heat it, then feed the solder wire into the heated area until there's a small glob of solder on the pad.
Re-heat the solder while holding the inductor in its outline, so that its end caps (the sides with the notches) are resting on the circuit board's pads.
The power inductor is symmetrical and can be soldered in either orientation, as long as the notches are above the pads.
Remove the iron, then remove the tweezers once the solder has cooled.

Step 26

Press the tip against the power inductor's second solder pad and the power inductor's second end cap for a few seconds to heat them both. Angle the tip so it has maximum contact with the pad and cap.
Feed the solder wire into the heated area until there's a small glob of solder joining the second end cap to its pad.
The power inductor's contact pads are underneath it, so the solder joint doesn't need to cover the entire end.

Step 27

Use tweezers to pick up one of the test rings and squeeze its leads together.
Insert the test ring leads into the hole labeled PWM on the front of the board.

Step 28

Repeat this process for the other test ring in the hole labeled SIN.

Step 29

Flip the board over so the test rings' leads are facing up.
Solder the test rings to the board.

Step 30

Align the toggle switch with the outline labeled ON on the front of the board, with the switch itself facing outwards.
Insert the switch's five pins into their holes in the board.

Step 31

Flip the board so the toggle switch's pins are facing up.
Solder the toggle switch to the board.

Step 32

Align the OLED female header strip with the outline labeled OLED on the board.
Insert the header's seven pins into their holes in the board.

Step 33

Flip the board over so the header strip's pins are facing up.
Solder the female header strip to the board.

Step 34

Align the terminal block with the outline labeled INPUT on the front of the board, with the terminal interface facing outwards.
Insert the block's two pins into their holes in the board.

Step 35

Flip the board over so the terminal block's pins are facing up.
Solder the terminal block to the board.

Step 36

Align the first adjustable resistor (labeled W204 on the top) with the outline labeled RP1 on the front of the board. The gold knob should be closest to the microcontroller.
The adjustable resistors are not symmetrical. The protruding edges and adjustable knob need to be aligned with their respective outline.
Insert the resistor's three pins into their holes in the board.

Step 37

Flip the board over so the resistor's pins are facing up.
Solder the first adjustable resistor to the board.

Step 38

Align the second adjustable resistor (labeled W501 on the top) with the outline labeled RP2 on the front of the board. The gold knob should be closest to the microcontroller.
Insert the resistor's three pins into their holes in the board.

Step 39

Flip the board over so the resistor's pins are facing up.
Solder the second adjustable resistor to the board.

Step 40

Align the encoder knob with the outline labeled EC11 on the front of the board. Orient it so the three leads at the top correspond with the three holes on the board under the MiNi-DSO label.
Insert the encoder's seven pins into their holes in the board.

Step 41

Flip the board over so the encoder's pins are facing up.
Solder the encoder knob to the board.

Step 42

In this step, you'll be soldering the male display connector onto the display board.
Align the male OLED display connector into the outline on the back of the display board. The shorter pins should be facing the board.
Insert the connector's seven shorter pins into their holes in the board.

Step 43

Flip the display board over so the connector's leads are facing up.
Solder the OLED display connector to the display board.

Step 44

Align the display's male pins with its female connector on the front of the board, so the display itself is over the microcontroller.
Push the pins fully into the connector.

Step 45

Before connecting the oscilloscope to power, visually inspect your work to make sure there are no bridged or incomplete solder joints to avoid damaging components.
Only the two pads labeled BAT should be empty.
Connect the oscilloscope to a power source with the included Micro USB cable.

Step 46

If your toggle switch is off, slide it to the ON position to power up your oscilloscope. You should see the display turn on and show "MiniDSO" at the top.
If the oscilloscope doesn't power on, check your joints to make sure none are bridged, damaged, or incomplete.

Step 47

Once the oscilloscope boots up, you should see a screen with a graph. Rotate the encoder knob to test its functionality.
Turn off the oscilloscope and unplug its USB cable once you've verified its functionality.

Step 48

Use your flush cutters to trim the test ring leads until they're no longer poking up past the solder joint from the back of the board.

Step 49

Repeat the last step to trim all the leads until they're no longer poking up past their solder joint from the back of the board.

Step 50

This is a great time to clean up any residue left from the solder. Apply some isopropyl alcohol to the solder joints and wipe with a lint-free cloth to soak up the flux and alcohol residue.

Step 51

The remaining steps show how to assemble the oscilloscope's case.
The case contains the following parts:
1x Bottom acrylic
1x Top acrylic
4x 11 mm screws
4x 7 mm screws
4x Nuts
4x Standoff posts

Step 52

Use your fingernail or tweezers to peel up an edge of the bottom acrylic's protective film and peel it off.
Repeat this process for the film on the other side.

Step 53

Repeat the previous step to remove the top acrylic's protective films.

Step 54

Insert one of the 11 mm screws into a hole in the bottom acrylic.

Step 55

Thread one of the nuts onto the screw until it's finger-tight.
Don't use tools to tighten the nut to avoid damaging the acrylic.
You can hold the screw with your finger or a screwdriver while tightening to ensure a snug fit.

Step 56

Repeat this process for the remaining three holes in the bottom acrylic.

Step 57

Align the circuit board's four corner holes with the screws protruding from the bottom acrylic. Orient the board so the back is facing the bottom acrylic.
Insert the four screws through their holes until the board sits flush with the nuts on the bottom case.

Step 58

Thread one of the standoff posts onto a screw protruding from the board until it's finger-tight against the board.
Don't use additional tools to tighten the standoff posts to avoid damaging the board.
Repeat this process for the other three standoff posts & screws.

Step 59

Grab the plastic pull tab on the OLED display's protective film and peel it off.

Step 60

Align the top acrylic with the four standoff posts' screw holes, the adjustable resistor knobs, and the terminal block screws.

Step 61

Use a screwdriver to screw one of the 7 mm screws into a standoff post until it's roughly finger-tight.
Screw the last three screws into the remaining standoff posts.

Step 62

Align the hole in the bottom of the knob cover with the encoder knob.
Insert the knob cover onto the encoder knob and push it down until it bottoms out.

Step 63

Reconnect the Micro USB cable to the oscilloscope.

Step 64

Congratulations! You now have a functioning mini oscilloscope.
Toggle the switch to the ON position to power up your oscilloscope.

Conclusion

You've taken a great step toward mastering the valuable and versatile skill of surface-mount and through-hole soldering. With this kit under your belt, you're well-equipped to tackle various electronics projects and repairs. Remember, practice makes perfect, so don't hesitate to experiment and refine your techniques.

To learn more soldering skills, click here.

If you need additional help, check out our Answers community.

Author

Nick Schultz

Member since: 24/03/24

19090 Reputation

Mini Digital Oscilloscope DIY Soldering Kit Assembly

Introduction

Tools

Parts

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