| Timed Night Light (Adjustable Auto-Shutoff) |
An adjustable timer that keeps a night light on for a set
period (10 seconds to 5 minutes), then automatically shuts it
off. Perfect for bedtime reading or helping children feel
secure as they fall asleep.
|
555 timer, monostable, RC timing, transistor switching |
1 |
| Homework Focus Timer (25-Minute with End-Beep) |
A two-stage timer that provides 25 minutes of silent focus
time, followed by a 2-second beep to alert you when time is
up. Designed for homework sessions or Pomodoro-style focus
blocks.
|
555 timer, monostable, RC timing, buzzer, edge detection |
1 |
| Traffic Light Sequencer (555 + 4017 Decade Counter) |
A realistic traffic light controller that sequences through
Green, Yellow, and Red using a 555 timer as a clock and a
CD4017 decade counter for state sequencing. No microcontroller
required.
|
555 timer, astable, decade counter, digital logic, diode OR |
1 |
| Automatic Night Light with Hysteresis (LDR + Comparator) |
An automatic night light that turns on in darkness and off in
bright light using a photoresistor (LDR) and an LM393
comparator. Hysteresis prevents flickering around the
threshold.
|
comparator, hysteresis, voltage divider, photoresistor |
1 |
| Fridge Door Alarm with Delay Timer (CD4060) |
An automatic alarm that beeps if the fridge door is left open
for more than about 30 seconds. A magnetic reed switch detects
the door, and a CD4060 counter with built-in oscillator
provides the delay.
|
binary counter, oscillator, magnetic sensor, buzzer |
1 |
| Turn-Taking Counter with 7-Segment Display |
A manual turn-taking counter that displays digits 0–9 on a
7-segment display. Press NEXT to advance the count and RESET
to return to zero. Uses a 555 monostable for debouncing.
|
555 timer, BCD counter, 7-segment driver, debouncing |
1 |
| Mailbox "Mail Arrived" Latching Indicator |
A latching indicator that lights an LED when the mailbox door
opens (mail delivered) and keeps it lit until manually reset.
A magnetic reed switch senses the door, and a CD4013 flip-flop
latches the ON state.
|
D flip-flop, latch, magnetic sensor, transistor driver |
1 |
| Three-Button Combination Lock |
An enhanced three-stage digital combination lock with hardware
button debouncing and jumper-configurable code selection.
Three buttons (A, B, C) can be assigned in any order as the
correct sequence using simple jumpers.
|
D flip-flop, state machine, debouncing, sequential logic |
1 |
| Bike Turn Signal and Brake-Priority Flasher |
A bicycle turn signal system with automatic flashing and brake
light override. A 555 timer drives NPN transistor stages for
left and right turn LEDs, selected via a DPDT switch.
|
555 timer, astable, transistor switching, diode logic |
1 |
| Fastest-Finger Quiz Buzzer Lockout (4 Players) |
A four-player quiz buzzer system that locks out all but the
first player who presses their button. Each player has an LED
indicator; once one player wins, others are blocked until a
master reset.
|
D flip-flop, AND gates, lockout logic, debouncing |
1 |
| Light-Controlled DC Motor Speed Controller |
A light-controlled PWM motor speed controller using a 555
timer, a photoresistor, two steering diodes, and a logic-level
MOSFET. Light level changes alter duty cycle, which controls
motor speed smoothly.
|
555 timer, PWM, MOSFET, photoresistor, flyback diode |
1 |
| Police Siren Circuit with Flashing LEDs |
A dual-555 police siren circuit with transistor-driven
red/blue LED flashers and a speaker output. IC1 generates a
low-frequency modulation signal; IC2 generates an audio tone
whose frequency is modulated by IC1.
|
555 timer, frequency modulation, transistor drivers, inverter |
1 |
