DIY Digital Electronic Scale Kit 1kg Precision Load Cell & 51 Microcontroller Soldering Project

Quick Introduction: Ever wondered how a digital scale actually converts physical weight into a number on a screen? Stop guessing and start building. The DIY Electronic Scale Kit strips away the mystery, allowing you to assemble a fully functional, high-precision weighing instrument from the component level up. Ideal for students and hobbyists, this kit teaches you the real-world application of Wheatstone bridges, 24-bit Analogue-to-Digital conversion, and microcontroller programming.

Detailed Specifications

• Microcontroller: STC15W408S (51 Series Architecture)

• Sensor Type: 1kg Aluminium Alloy Parallel Beam Load Cell

• ADC Module: HX711 (24-Bit Precision)

• Display: 4-Digit 0.56" Red LED (7-Segment)

• Measurement Range: 0g - 1000g (1kg)

• Power Input: 5V DC (via DC-005 Jack or USB)

• Dimensions: 85mm x 85mm x 45mm (Approx)

• PCB Material: Double-sided FR-4 Fibreglass (1.6mm)

Quality Advantage & Differentiation: Why build this instead of buying a cheap scale? Most budget scales use "black blob" (COB) chips and paper-thin PCBs that are impossible to repair or study. This kit features a FR-4 PCB with clear white silkscreen labelling and plated-through holes, ensuring a durable build that can withstand repeated handling. It utilises an HX711 Module—the industry standard for weighing applications—rather than a cheap generic substitute, guaranteeing stable readings and lower noise interference.

Key Applications & Usage: This kit is designed for STEM Education and Technical Training. It serves as an excellent final project for electronics courses, teaching students how to solder through-hole components, interface analogue sensors with digital logic, and calibrate measurement devices. Once assembled, it functions as a handy desktop scale for weighing small parts, screws, or chemistry ingredients.

Popular Project Ideas

• Classroom Physics Lab: Demonstrate the relationship between strain, resistance, and voltage.

• IoT Inventory System: Modify the code (programmer required) to send weight data to a PC via UART.

• Soldering Certification: Use as a test board for precision soldering of IC sockets and connectors.

What's Included & Required

• Accessories Included: 1x Main PCB, 1x 1kg Load Cell, 1x HX711 Module, 1x STC15W408S MCU, 1x Acrylic Case Set, 1x USB Power Cable, Resistors/Capacitors/LEDs.

• Additional Required: Soldering Iron, Solder Wire, Wire Cutters, 5V USB Power Source (Phone Charger).

Open-Source Compatibility The heart of this kit is the STC15W408S, a popular 8051-based microcontroller. While it comes pre-programmed, advanced users can re-flash it using a USB-TTL adapter (not included) and the Keil C51 environment. The HX711 is also fully compatible with Arduino, so you can potentially repurpose the load cell and ADC module for Arduino-based weighing projects later.

Helpful Tutorials & Resources:

• DIY Weighing Scale Kit _Assembly Manual & Schematic

VIRTUAL TECHNICIAN:

• Safety Inference (Voltage):

  • WARNING: The system runs on strictly 5V DC.

  • Do NOT connect a 9V battery or a 12V adapter directly to the DC jack. Doing so will permanently fry the STC15W408S microcontroller and the LED display.

• Wiring Interface Guide:

  • Load Cell to PCB Connection:

    • Red Wire -> E+ (Excitation Positive / VCC)

    • Black Wire -> E- (Excitation Negative / GND)

    • Green Wire -> A+ (Signal Positive)

    • White Wire -> A- (Signal Negative)

  • Note: If the weight reading decreases when you push down, swap the Green and White wires.

• Mechanical Assembly Tip:

  • Load Cell Orientation: The aluminium bar has an arrow sticker. This arrow MUST POINT DOWN towards the table.

  • Cantilever Setup: Ensure you use the included spacers. The load cell should NOT touch the base plate in the centre. It must be attached only at the ends (Z-shape) to allow it to bend.