This project focuses on designing and building a laboratory power supply with adjustable output voltage and integrated measurement of both voltage and load current. The device serves as a versatile tool for powering and diagnosing various electronic circuits. Special attention was given to precise voltage regulation, accurate measurements, and stable operation. s
- Input Voltage: 230V AC, 50Hz
- Output Voltage Range: 1.3V – 15V
- Maximum Output Current: 0.5A
- Current Measurement Resolution: 1mA
- Control: Voltage adjustment and parameter reading via computer
- Voltage Regulation: Manual, using a potentiometer
- Display: Voltage measurement shown on a screen
The circuit consists of multiple sections:
- Power Supply and Rectification
- Microcontroller and User Interface
- Voltage Level Adjustment
- Voltage Transmission
- Voltage Measurement and Noise Suppression
- Current Measurement via a Series Resistor
A schematic of the circuit is included in the documentation.
The power supply uses a 230V to 12V transformer, followed by a KBP02G bridge rectifier for full-wave rectification. A 4700µF capacitor (C1) smooths voltage fluctuations, and C2 acts as a decoupling capacitor. The supply voltage powers an LM358 operational amplifier, an Arduino Uno microcontroller, and other circuit components.
Voltage regulation is performed using an LM317T adjustable voltage regulator, with control signals processed by the microcontroller. A DAC (Digital-to-Analog Converter) controlled via I2C is used to set the output voltage. A non-inverting operational amplifier scales the DAC output to drive the LM317T, enabling software-based voltage adjustment.
For current measurement, a series resistor (R1) is used to determine voltage drop, which is then amplified using a differential amplifier. The microcontroller calculates the current using Ohm's Law.
User interaction is facilitated through a potentiometer (RV1) for manual voltage adjustment and a three-digit 7-segment display for real-time parameter visualization.
The Arduino Uno is programmed using C++ in Arduino IDE. The software consists of two main modules:
- Main Module: Reads voltage and current values, processes signals, and communicates with the computer.
- Display Module: Handles the 7-segment display, efficiently updating digits to minimize memory usage.
The software also includes an optional feature to generate sinusoidal waveforms, which can be activated by modifying specific code sections.
Below are different perspectives of the assembled device:
