Weekend Electronics Projects for Students
Welcome to our weekend project hub! These hands-on electronics projects are designed for students who want to explore circuits, components, and real-world engineering concepts. Grab your components and let's build something awesome!
Project 1: PWM Signal Generator Using SG3525
The SG3525 is a popular Pulse Width Modulation (PWM) controller IC widely used in power electronics. In this project, you'll build a basic PWM generator circuit that you can use to control motor speed, LED brightness, or as a foundation for a DC-DC converter.
Circuit Diagram
Pin Out
Internal Structure
40kHz Circuit Diagram
Note: Always double-check pin numbers on your SG3525 datasheet before wiring.
Components Needed
| Component | Value / Part No. | Quantity | Function |
|---|---|---|---|
| SG3525 IC | SG3525AN | 1 | The main PWM controller chip. |
| Resistor R1 | 10kΩ | 1 | Pull-up resistor for the output stage. |
| Resistor R2 (RT) | 10kΩ – 100kΩ (variable) | 1 | Timing resistor. Sets the oscillator frequency with C2. |
| Resistor R3 | 1kΩ | 1 | Connects inverting input (Pin 1) to GND. |
| Resistor R4 | 10kΩ | 1 | Connects Vref (Pin 16) to non-inverting input (Pin 2). |
| Potentiometer (RV1) | 10kΩ | 1 | Adjusts the duty cycle of the output signal. |
| Capacitor C1 | 100µF / 25V electrolytic | 1 | Power supply filter capacitor. |
| Capacitor C2 (CT) | 10nF – 100nF ceramic | 1 | Timing capacitor. Sets oscillator frequency with R2. |
| Capacitor C3 (Soft Start) | 0.1µF ceramic | 1 | Soft-start capacitor connected to Pin 8. |
| N-Channel MOSFET Q1, Q2 | IRF540N or similar | 2 | Power switching transistors driven by SG3525 outputs. |
| Diode D1, D2 | 1N4007 or Schottky 1N5819 | 2 | Flyback diodes to protect MOSFETs from voltage spikes. |
| LED (optional) | Any color, 5mm | 1 | Visual indicator to observe PWM dimming effect. |
| Resistor R5 (LED current limiter) | 330Ω | 1 | Limits current through the LED. |
| DC Power Supply | 12V DC, 1A minimum | 1 | Powers the entire circuit. |
| Breadboard | Full-size or half-size | 1 | Prototyping board for assembling the circuit. |
| Jumper Wires | Male-to-male | 1 set | Used to make connections on the breadboard. |
How It Works
The SG3525 uses its internal oscillator (set by R2 and C2) to generate a triangle wave. This is compared with a reference voltage (set via the potentiometer on Pin 2) by the internal error amplifier. The result is a PWM square wave on Pins 11 and 14. By turning the potentiometer, you change the duty cycle — which controls how much power reaches your load.
Frequency Formula: f ≈ 1 / (R_T × C_T)
More Projects Coming Soon!
Stay tuned for more weekend projects including:
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