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Hardware Design

Electronics

Architecture Overview

Electronics block diagram

Electronics block diagram

The system is built around a electronic design, centered on an ATmega328P microcontroller. It uses a DAC to control current draw, and an ADC to monitor voltage and current. The power stage is built using power MOSFETs and shunt resistors.

PCBs:

  • Main board: responsible for main funcionalities of the load

Main PCB photo

  • Front board: responsible for user input with the rotary encoder and switching the voltage measurement circuitry between the main and sense terminals

Front PCB photo

  • Converter board: responsible for user input with the rotary encoder and switching the voltage measurement circuitry between the main and sense terminals

Arduino angle view

Arduino top view

Arduino bottom view

Inputs and Interfaces

  • Power input: Up to 50 V DC, 8 A
  • Remote voltage sensing: Compensates cable losses
  • Trigger input: 0–5 V for switching load states in step response mode
  • Power input (AC): 230 V AC, powering the internal transformer

User Interface

  • Rotary encoder with push-button
  • Numeric keypad
  • LCD display for measurements and settings
  • Mode and source selection switches

Mechanical

Front panel wireframe

Back panel wireframe

Cooling

A temperature-controlled fan manages heat dissipation, automatically adjusting speed based on heatsink temperature. Over-temperature protection shuts off the load above 50°C.

Enclosure

  • Custom-made metal case (CNC cut and bent steel)
  • 3D-printed front panel for easy mounting of connectors and display