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Breathing Heart Solder Kit Assembly Guide§

Welcome to the assembly guide for the Breathing Heart Solder Kit! Whether you're a beginner or a seasoned maker, this guide will walk you step-by-step through the process of building your very own LED breathing heart circuit. The PCB is shaped like a heart and, when assembled, will create a calming pulsing light effect using simple analog electronics.

By the end of this guide, you will have:

  • Practiced through-hole soldering
  • Learned to identify and place resistors, transistors, capacitors, ICs, and more
  • Assembled a beautiful heart-shaped breathing LED circuit

🛠 Required tools: soldering iron, solder, flush cutters, and optionally tweezers.

Resistor Color Codes§

Understanding the color bands on resistors is crucial for placing the correct components. Below is a quick reference for the resistor values used in this kit. You can identify them either by reading the color bands or by measuring with a multimeter.

Value Color Bands Schematic
47kΩ Yellow, Violet, Orange, Gold
10kΩ Brown, Black, Orange, Gold
22Ω Red, Red, Black, Gold
100kΩ Brown, Black, Yellow, Gold

💡 Tip: The fourth band (gold) indicates a tolerance of ±5%.
🧰 Alternative: Use a multimeter to measure resistance directly if you're unsure.

LED Orientation and Polarity§

LEDs (Light Emitting Diodes) are polarized components, meaning they must be installed in the correct direction to work properly.

How to identify LED legs§

  • Long leg = Positive (+) → called the anode
  • Short leg = Negative (−) → called the cathode

How to match the LED to the PCB§

Each LED slot on the PCB shows a diode symbol like this:

  • The flat edge of the triangle (left side in the symbol) is the cathode (−) → match this with the short leg of the LED.
  • The open tip of the triangle (right side) is the anode (+) → match this with the long leg of the LED.

Visual Guide§

⚠️ If inserted backwards, the LED will not light up. Always verify orientation before soldering!

Step-by-step Instructions§

Image Description
PCB Overview Step 1: Identify Your PCB
Start by identifying the front side of the PCB. This is where all the components will be placed and soldered. Take a moment to get familiar with the component labels.
47kΩ Resistors Step 2: Solder 47kΩ Resistors (R1, R2, R4)
Locate the three 47kΩ resistors. These are marked with color bands: yellow, violet, orange, gold. Insert and solder them in the positions labeled R1, R2, and R4.
10kΩ Resistor Step 3: Solder 10kΩ Resistor (R6)
Find the resistor marked brown, black, orange, gold and solder it into the R6 position.
22Ω Resistor Step 4: Solder 22Ω Resistor (R5)
This resistor is marked red, red, black, gold. Solder it into the R5 spot on the PCB.
100kΩ Resistor Step 5: Solder 100kΩ Resistor (R3)
The 100kΩ resistor has the color code brown, black, yellow, gold. Place it in the R3 slot.
Insert IC Step 6: Insert LM358N IC (U1)
Carefully insert the LM358N chip into the U1 position. Make sure the notch or dot on the chip matches the notch printed on the PCB.
Adjustable Resistor Step 7: Solder Adjustable Resistor (VR1)
Insert the blue adjustable resistor (also known as a potentiometer) into the VR1 slot.
Transistor Step 8: Solder Transistor (Q1)
The transistor goes into the Q1 position. Make sure to align the flat side of the component with the flat side printed on the board.
Electrolytic Capacitor Step 9: Solder Electrolytic Capacitor (C1)
Pay attention to polarity! The longer leg is positive and should go into the hole marked with a plus (+). Also check the photo in the next step for orientation
Capacitor Close-up Step 10: Check Capacitor Orientation
Double-check that the negative stripe on the capacitor aligns with the negative marking on the PCB.
Tactile Switch Step 11: Solder the Switch (S1)
Insert the tactile switch into the S1 slot labeled "power". Make sure it is pushed in all the way before soldering.
LED Orientation Step 12: Place All LEDs
Insert the LEDs into the board. Make sure to match polarity: the long leg goes in the round hole (+), and the short leg in the square hole (-).
All LEDs Placed Step 13: Verify LED Placement
All 20 LEDs should now be in place. Double-check that all the long legs are on the correct side before soldering.
All LEDs Placed Step 14: Solder Battery Box
Solder the battery box wires: red to + and black to -