Project Hub /Basic Analog & Power Electronics/Discrete & Component Electronics/Fan Cooling For Improved Performance Of Refrigerators

Intermediate

ANALOG / DISCRETE

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Fan Cooling For Improved Performance Of Refrigerators

This project implements an automated fan-cooling system that attaches to refrigerator side walls and switches on when the compressor operates, improving heat dissipation and cooling efficiency.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
110 RPM Single Shaft BO Motor – Straight Rs. 99.00
DC Motor Plastic Fan Blade Rs. 19.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: Transformer
Diodes (1N4007 / 1N4148 / Schottky / Zener)
Capacitors
Transistors (BC547 / 2N2222 / TIP / MOSFET)
Screws / Nuts / Standoffs / Hardware
12V instrument cooling fans

Browse all components

How It Works

This automated fan-cooling system monitors refrigerator compressor activity using a 5A to 5mA Current Transformer (CT) clamped around the compressor's power line. When the compressor draws current, the CT produces a proportional secondary current. This AC signal is converted to DC via a diode bridge rectifier formed by D1 through D4 (1N4007) and filtered by a 0.47µF box capacitor (C1) along with a resistive voltage divider network utilizing R1 and R2 (both 4.7kΩ). The resulting control voltage biases transistor T1 (BC546), which acts as a signal amplifier. When T1 turns on, it drives the larger TIP31C power transistor (T2, equipped with a small heat-sink). T2 acts as a high-current electronic switch that controls the pair of 12V instrument cooling fans. A 330Ω, 1W resistor (R3) helps manage power distribution, while diode D5 functions as a free-wheeling (flyback) diode connected across the inductive fan loads to protect transistor T2 from voltage spikes when the fans switch off. Together, these components ensure that the cooling fans operate automatically whenever the compressor runs, assisting with heat dissipation.

Why Build This

Enhance household refrigerator energy efficiency and lower overall power consumption by improving condenser heat dissipation.

Extend the operational lifespan of the compressor by reducing thermal stress in confined kitchen spaces.

Gain practical undergraduate-level engineering experience integrating analog current sensing with discrete power-switching transistor circuits.

Real-World Application

Household refrigerators, energy saving in kitchen appliances, extending compressor life, improving cooling efficiency in confined spaces.

Skills You'll Learn

Current sensing via current transformers

AC-to-DC rectification and filtering

transistor biasing and signal amplification

inductive load switching with flyback diodes

discrete power electronics design

Safety Precautions

Do not disconnect the burden resistor from the CT terminals during operation; without the burden resistor, the CT will generate a high voltage and the coil may burn out. Exercise caution when working with circuits connected near mains or compressor wiring.

Technology Tags

CURRENT TRANSFORMER

TRANSISTOR

FULL-WAVE RECTIFIER

COOLING FAN

COMPRESSOR MONITORING

Frequently Asked Questions

Why is a current transformer used instead of directly connecting to the microcontroller?

This project is entirely analog and discrete, meaning it does not use a microcontroller; the current transformer safely senses the compressor's electrical draw without requiring a direct, intrusive electrical splice into the high-voltage AC mains line.

What is the purpose of the 1N4007 diode D5 across the fans?

D5 acts as a free-wheeling or flyback diode, providing a safe discharge path for the magnetic energy stored in the 12V fans when they turn off, which protects transistor T2 from voltage spikes.

Why does the TIP31C transistor require a small heat-sink?

The TIP31C handles the higher current demanded by running two 12V instrument cooling fans simultaneously, and a heat-sink helps dissipate the resulting thermal energy during continuous operation.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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