🔌 100 ELECTRONICS MINI PROJECTS

1. Automatic Night Lamp using LDR

Turns ON a lamp automatically when ambient light falls below a set level.
Main components: LDR, BC547, Relay

2. Clap Switch Circuit

Controls an appliance using sound pulses detected by a microphone.
Main components: Condenser Mic, BC547, 555 Timer

3. Touch-Based Switch

Activates a load when a human touch is detected due to body capacitance.
Main components: BC547, High-value resistors

4. Temperature Controlled Fan

Fan speed changes based on surrounding temperature.
Main components: Thermistor, LM358, BC547

5. Fire Alarm Circuit

Detects abnormal heat and triggers an alarm buzzer.
Main components: Thermistor, 555 Timer

6. Water Level Indicator

Indicates different water levels in a tank using LEDs.
Main components: BC547, LEDs, Resistors

7. Water Level Controller

Automatically turns ON/OFF motor based on tank level.
Main components: BC547, Relay

8. Emergency Light Circuit

Provides automatic lighting during power failure.
Main components: BC547, Diodes, Rechargeable battery

9. Doorbell with Melody Generator

Generates a musical tone instead of a normal bell sound.
Main components: UM66 IC, BC547

10. Light Activated Alarm

Triggers an alarm when light falls on the sensor.
Main components: LDR, BC547, Buzzer

11. IR Object Detection Circuit

Detects the presence of nearby objects using IR reflection.
Main components: IR LED, Photodiode, BC547

12. Laser Security Alarm

Alarm triggers when a laser beam is interrupted.
Main components: LDR, BC547, Laser module

13. Electronic Dice

Displays random numbers using LEDs on every trigger.
Main components: 555 Timer, CD4017

14. Traffic Light Controller

Simulates traffic light sequence using counters.
Main components: 555 Timer, CD4017

15. Automatic Street Light

Street lights turn ON at night and OFF during daytime.
Main components: LDR, BC547, Relay

16. Battery Level Indicator

Displays battery voltage level using LEDs.
Main components: LM358, LEDs

17. Over Voltage Protection Circuit

Disconnects load when input voltage exceeds safe limit.
Main components: Zener diode, BC547, Relay

18. Under Voltage Protection Circuit

Protects devices from low voltage operation.
Main components: Zener diode, BC547

19. Simple Inverter Circuit

Converts DC into AC for low-power loads.
Main components: Transistors, Transformer

20. DC Motor Speed Controller

Controls motor speed using PWM technique.
Main components: 555 Timer, BC547

21. Electronic Lock using Key Switch

Allows access only with correct key combination.
Main components: BC547, Push buttons

22. Burglar Alarm Circuit

Triggers alarm on unauthorized entry.
Main components: BC547, Magnetic switch

23. Heat Sensor Alarm

Activates alarm when temperature crosses threshold.
Main components: Thermistor, BC547

24. Automatic Hand Dryer

Blows air when hands are detected.
Main components: IR sensor, BC547, Relay

25. LED Flasher Circuit

Flashes LEDs at adjustable speed.
Main components: 555 Timer

26. Sequential LED Chaser

LEDs glow in running pattern.
Main components: CD4017, 555 Timer

27. Rain Alarm Circuit

Detects rainfall and activates alarm.
Main components: Rain sensor, BC547

28. Telephone Ring Indicator

Indicates incoming call visually.
Main components: Optocoupler, BC547

29. Power Supply using 7805

Provides regulated 5V DC output.
Main components: 7805, Diodes, Capacitors

30. Adjustable Power Supply

Variable output voltage using regulator IC.
Main components: LM317

31. Audio Amplifier Circuit

Amplifies low-level audio signals.
Main components: BC547, BC557

32. Low Battery Indicator

Warns when battery voltage drops.
Main components: LM358, LEDs

33. Electronic Voting Machine (Basic)

Counts votes using push buttons and LEDs.
Main components: CD4017, BC547

34. Continuity Tester

Checks electrical continuity in circuits.
Main components: BC547, Buzzer

35. Smoke Detector

Detects smoke presence using gas sensor.
Main components: MQ-2, BC547

36. Timer Switch

Turns OFF load after preset time.
Main components: 555 Timer, Relay

37. PWM Generator

Generates variable duty cycle signal.
Main components: 555 Timer

38. Audio Level Indicator

Displays audio strength using LEDs.
Main components: LM3914

39. Voltage Doubler Circuit

Doubles input voltage using diodes.
Main components: Diodes, Capacitors

40. Current Limiting Circuit

Protects load from excess current.
Main components: Transistors, Resistors

41. Light Intensity Meter

Measures ambient light level.
Main components: LDR, LM358

42. Touch-Free Switch

Switches load using proximity sensing.
Main components: IR sensor, BC547

43. Electronic Fuse

Cuts supply instantly during overload.
Main components: BC547, Relay

44. Signal Generator

Generates square wave signals.
Main components: 555 Timer

45. Door Open Indicator

Indicates door status visually.
Main components: Reed switch, BC547

46. Sound Activated Switch

Controls appliances using sound.
Main components: Mic, BC547

47. Automatic Bell System

Rings bell at preset intervals.
Main components: 555 Timer, Relay

48. DC Fan Controller

Manually controls fan speed.
Main components: BC547, Potentiometer

49. Battery Charger Circuit

Charges battery with protection.
Main components: Diodes, Transistor

50. AC Mains Detector

Detects presence of AC supply.
Main components: Optocoupler

51. Automatic Pump Controller

Controls a water pump automatically based on tank level.
Main components: BC547, Relay, Probes

52. Power Failure Indicator

Indicates when mains power goes OFF.
Main components: Optocoupler, BC547

53. Battery Reverse Polarity Protection

Protects circuit from accidental battery reversal.
Main components: Diode, BC547

54. Electronic Door Alarm

Activates alarm when door is opened.
Main components: Reed switch, BC547

55. High Temperature Cut-Off Circuit

Disconnects load when temperature exceeds limit.
Main components: Thermistor, LM358, Relay

56. Automatic Light Dimmer

Adjusts lamp brightness based on ambient light.
Main components: LDR, LM358, TRIAC

57. Power ON Indicator with Delay

Provides delayed indication after power stabilization.
Main components: 555 Timer, BC547

58. Adjustable Delay Timer

Generates adjustable ON/OFF delay.
Main components: 555 Timer, Potentiometer

59. Simple Metal Detector

Detects presence of metal objects using inductance change.
Main components: 555 Timer, Inductor

60. Proximity Sensor Circuit

Detects nearby objects without contact.
Main components: IR LED, Photodiode, BC547

61. DC Motor Direction Controller

Controls clockwise and anticlockwise motor rotation.
Main components: Transistors, DPDT relay

62. Automatic Cooling System

Activates cooling fan when temperature rises.
Main components: LM358, Thermistor

63. Light Failure Indicator

Detects failure of a lamp in a circuit.
Main components: BC547, Resistors

64. Electronic Lock using Push Buttons

Unlocks only with correct button sequence.
Main components: CD4017, BC547

65. Overload Indicator

Indicates when current exceeds safe value.
Main components: Shunt resistor, BC547

66. Electronic Siren Circuit

Generates rising and falling siren sound.
Main components: 555 Timer

67. Battery Charging Status Indicator

Shows charging and full-charge condition.
Main components: LM358, LEDs

68. Automatic Room Light Controller

Lights turn ON when motion is detected.
Main components: PIR sensor, BC547

69. DC Voltage Monitor

Continuously monitors voltage level.
Main components: LM358, LEDs

70. Zero Crossing Detector

Detects AC zero crossing for control applications.
Main components: Op-Amp 741, Diodes

71. Electronic Fan Regulator

Controls fan speed electronically instead of resistive method.
Main components: TRIAC, DIAC

72. Touch Operated Bell

Bell rings when a touch plate is touched.
Main components: BC547, Resistors

73. Simple Oscillator Circuit

Generates continuous oscillations.
Main components: 555 Timer

74. Phase Indicator Circuit

Indicates presence of AC phase.
Main components: Neon lamp, Resistors

75. Automatic Battery Charger Cut-Off

Stops charging when battery is fully charged.
Main components: LM358, Relay

76. Electronic Buzzer Driver

Drives buzzer with sufficient current.
Main components: BC547

77. DC Load Tester

Tests power supply load handling capability.
Main components: Power transistor, Resistors

78. Audio Signal Tracer

Helps locate faults in audio circuits.
Main components: BC547, Speaker

79. Automatic Gate Control (Model)

Controls gate opening and closing automatically.
Main components: IR sensor, Relay

80. Light Based Fan Controller

Fan speed varies with light intensity.
Main components: LDR, LM358

81. Simple Digital Clock (IC Based)

Displays time using counters and displays.
Main components: IC 555, Counters

82. DC Power Failure Alarm

Triggers alarm during power outage.
Main components: BC547, Buzzer

83. Automatic Bell for Schools

Operates bell at fixed time intervals.
Main components: 555 Timer, Relay

84. Electronic Door Access Indicator

Indicates authorized or unauthorized access.
Main components: BC547, LEDs

85. Temperature Indicator using LEDs

Shows temperature range visually.
Main components: LM358, LEDs

86. Night Activated Alarm

Alarm triggers only during nighttime.
Main components: LDR, BC547

87. Load ON/OFF Indicator

Displays load status clearly.
Main components: Optocoupler, LED

88. Signal Strength Indicator

Indicates signal level using LEDs.
Main components: LM3914

89. Electronic Water Overflow Alarm

Alerts when tank overflows.
Main components: BC547, Buzzer

90. AC Line Voltage Monitor

Monitors AC voltage presence and variation.
Main components: Transformer, LM358

91. Simple UPS Changeover Circuit

Switches load between mains and battery.
Main components: Relay, BC547

92. Touchless Hand Wash Timer

Controls water flow for fixed duration.
Main components: IR sensor, 555 Timer

93. DC Motor Soft Starter

Reduces inrush current during motor start.
Main components: Transistors, RC network

94. Electronic Trip Circuit

Trips supply under fault conditions.
Main components: BC547, Relay

95. Sound Level Alarm

Triggers alarm when sound exceeds threshold.
Main components: Mic, LM358

96. Simple Frequency Generator

Generates adjustable frequency output.
Main components: 555 Timer

97. Electronic Polarity Tester

Identifies polarity of DC supply.
Main components: BC547, LEDs

98. Automatic Lamp Flasher

Flashes lamp at regular intervals.
Main components: 555 Timer, Relay

99. Low Cost Signal Amplifier

Amplifies weak sensor signals.
Main components: BC547, Resistors

100. Basic Process Control Panel (Model)

Demonstrates sensing, control, and indication.
Main components: LM358, BC547, Relays

OP-AMP Based Projects

🌡️ TEMPERATURE & THERMAL SYSTEMS

RTD Signal Conditioning System
Amplifies low-level RTD resistance changes for accurate temperature measurement.
Components: RTD, Op-Amp instrumentation amplifier.
Thermocouple Amplifier with Cold Junction Compensation
Boosts micro-volt thermocouple output using multi-stage op-amp design.
Components: Thermocouple, Op-Amp, reference diode.
Thermistor-Based Temperature Alarm
Compares thermistor voltage against reference to trigger alert.
Components: Thermistor, Op-Amp comparator.
Diode Temperature Sensor Using Op-Amp
Uses diode voltage variation with temperature amplified by op-amp.
Components: PN diode, Op-Amp.

💨 GAS, AIR & ENVIRONMENTAL MONITORING

Gas Leakage Detection Circuit
Amplifies MQ sensor output and activates alarm when threshold exceeds.
Components: MQ sensor, Op-Amp comparator.
Smoke Density Measurement System
Processes photoelectric smoke sensor signals using op-amps.
Components: IR LED, photodiode, Op-Amp.
Air Pressure Signal Conditioning System
Amplifies pressure sensor output for monitoring applications.
Components: Pressure sensor, Op-Amp.
Chemical Concentration Measurement Circuit
Conditions electrochemical sensor output using op-amp buffering.
Components: Chemical sensor, Op-Amp.

🌧️ WATER, LIQUID & MOISTURE SYSTEMS

Rain Detection System with Adjustable Sensitivity
Op-amp amplifies rain sensor signal and allows sensitivity tuning.
Components: Rain sensor, Op-Amp.
Water Level Detection Using Conductivity Probes
Detects water level using resistance change and op-amp comparator.
Components: Probes, Op-Amp.
pH Sensor Interface Circuit
Buffers high-impedance pH probe output using op-amp follower.
Components: pH electrode, Op-Amp.

🧍 HUMAN & BIOMEDICAL APPLICATIONS

Heartbeat Signal Conditioning Circuit
Filters and amplifies weak pulse sensor signals.
Components: Pulse sensor, Op-Amp filter.
Sound Level (Decibel) Meter
Amplifies microphone signal and converts it to RMS value.
Components: Electret mic, Op-Amp.
Human Touch Detection Using Op-Amp
Detects touch using body capacitance and comparator logic.
Components: Op-Amp, resistors.
Human Presence Detection Using Capacitive Sensing
Detects proximity without PIR using op-amp sensitivity.
Components: Op-Amp, electrodes.

🧲 MAGNETIC, MOTION & FORCE SYSTEMS

Hall Effect Sensor Signal Amplifier
Boosts Hall sensor output for speed or position sensing.
Components: Hall sensor, Op-Amp.
Magnetic Field Strength Measurement System
Measures magnetic intensity using amplified sensor output.
Components: Hall sensor, Op-Amp.
PIR Motion Sensor Amplifier Module
Improves PIR sensor range using band-pass op-amp filters.
Components: PIR sensor, Op-Amp.
Piezoelectric Vibration Detection Circuit
Amplifies piezo disc output to detect vibrations or shocks.
Components: Piezo disc, Op-Amp.
Strain Gauge Load Cell Amplifier
Instrumentation amplifier built using op-amps for force sensing.
Components: Strain gauge, Op-Amp.

🌞 OPTICAL & LIGHT-BASED SYSTEMS

Solar Radiation Measurement System
Converts photodiode current to voltage using op-amp.
Components: Photodiode, Op-Amp (TIA).
Flame Detection System
Amplifies IR flame sensor output for fire detection.
Components: IR sensor, Op-Amp.
IR Proximity Signal Conditioning Circuit
Enhances IR sensor range using op-amp amplification.
Components: IR sensor, Op-Amp.
Infrared Temperature Sensor Interface
Conditions IR thermal sensor output for accurate readings.
Components: IR sensor, Op-Amp.

📏 MEASUREMENT & INSTRUMENTATION

Distance Measurement Signal Conditioning System
Amplifies analog distance sensor output for better resolution.
Components: Distance sensor, Op-Amp.
Wind Speed Detection Using Pressure Differential
Measures airflow speed using pressure sensor amplification.
Components: Pressure sensor, Op-Amp.
Analog Comparator-Based Threshold Monitoring System
Monitors sensor voltage crossing preset limits.
Components: Op-Amp comparator.
Instrumentation Amplifier Using Op-Amps
High-precision amplifier for low-level sensor signals.
Components: Multiple Op-Amps.

🔥 SAFETY & ALERT SYSTEMS

Temperature-Based Fire Alert Circuit
Triggers alarm when temperature exceeds safe limit.
Components: Thermistor, Op-Amp.
Over-Voltage Protection Circuit Using Op-Amp
Protects circuits by cutting off when voltage rises.
Components: Op-Amp, relay.
Over-Current Detection Circuit
Detects abnormal current using shunt resistor and op-amp.
Components: Shunt resistor, Op-Amp.

🧠 SENSOR-CREATION / SPECIAL CONCEPT PROJECTS

Capacitive Level Sensor Using Op-Amp
Measures liquid level using capacitance change.
Concept: Sensor made using Op-Amp.
Resistance-Based Moisture Sensor Interface
Detects soil moisture using resistance variation.
Concept: Analog sensing with Op-Amp.
Light Intensity Meter Using LDR & Op-Amp
Amplifies LDR voltage for lux measurement.
Components: LDR, Op-Amp.
Analog Signal Conditioner for Multi-Sensor Systems
Single op-amp board for conditioning multiple sensors.
Application: Industrial measurement.

100+ ECE MINI PROJECTS using (ICs, Transistors , Op-amps ... & many more)