Build Your Own Oscilloscope – Part 4 | Soldering Tips & PCB Progress

Foundation

Proverbs 3:5–6 (KJV)
Trust in the Lord with all thine heart; and lean not unto thine own understanding.
In all thy ways acknowledge him, and he shall direct thy paths.

🧠 Lesson Overview

Welcome to Part 4 of the DSO138 DIY Oscilloscope Build!

In this lesson, we move further along in assembling the oscilloscope by installing key components including:

  • Trimmer capacitors
  • Inductor
  • Electrolytic capacitors
  • Power connector
  • Pin headers and connectors

This is where the board really starts coming together.

  • Soldering is a skill—mistakes are part of the process

▶️ Watch the Full Video

 

🛠️ Lab Build – Step by Step

🔹 Installing Trimmer Capacitors (C4 & C6)

  • These are adjustable capacitors (5–30 pF)
  • Used for fine-tuning the circuit
  • No polarity required
  • Align carefully with the silkscreen shape and notch

💡 Tip: These components allow for small adjustments later, likely during calibration.

🔹 Installing the Inductor (L2)

  • A 1 mH power inductor
  • No polarity (just a coil of wire)
  • Place in correct board location (L2)

📘 Quick Note: Inductors store energy in a magnetic field and are measured in Henrys

🔹 Installing Electrolytic Capacitors

  • Example: 100 µF, 16V capacitors
  • Polarity matters!
    • Long lead = Positive
    • Short lead = Negative
    • White stripe = Negative
  • Board indicators:
    • Square pad = Positive
    • Round pad = Negative

⚠️ Warning: Installing backwards can cause capacitors to fail or pop

🔹 Soldering Tips Reinforced

  • Heat both the pad and lead
  • Look for a clean, shiny joint
  • Avoid:
    • Cold solder joints
    • Solder bridges
    • Loose debris (solder balls)

💡 Pro Tip: Clean your board before powering it on

🔹 Installing the Power Connector (J10)

  • DC input connector for the oscilloscope
  • Carefully align (only fits one location)
  • Use tape to hold it in place while soldering

🔹 Optional Pin Headers (J5, J6, J7, J8)

  • Used for:
    • Testing
    • Expansion
    • Possible calibration
  • Not required for operation, but recommended to install

💡 Tip:
Use tape or tack soldering to keep headers straight

🔹 Installing Large Header (J3)

  • Multi-pin connector for display interface
  • Take your time—many pins close together

⚠️ Watch for:

  • Solder bridges
  • Misalignment

🔹 Installing BNC Connector (J1)

  • Input signal connector for oscilloscope probe
  • Requires more heat due to larger metal mass

💡 Tip: Be patient—this takes longer to solder properly

🔹 Test Signal Ring (J2)

  • Create a small loop using trimmed component lead
  • Acts as a test/calibration point
  • Outputs a signal (approx. 1 kHz)

🔹 Shorting JP3

  • Simply connect the two pads with solder
  • Required step for proper operation

🔬 Key Lessons Learned

  • Double-check polarity on all capacitors
  • Take your time with tight pin layouts
  • Use tape to stabilize components
  • Clean up solder bridges immediately
  • Soldering is a skill—mistakes are part of the process

🌐 More Lessons & Notes

Visit the full lesson library:
👉 https://buildcircuitswithrich.com

⏭️ What’s Next (Part 5)

In the next lesson, we will:

  • Assemble the display board
  • Connect it to the main PCB
  • Move closer to powering up the oscilloscope

💬 Final Thoughts

This build is really starting to come together. Each step builds confidence and skill—not just in assembling a kit, but in understanding how real electronic systems are built.

👉 Now… back to the lab. 😄

Want more electronics lessons?

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