“This project demonstrates the basics of digital logic, the characteristics of a NE555 timer, and demonstrates how binary numbers are counted. The components used are: a NE555 timer, a 12-bit ripple counter, two 2-input NOR gates, a 4-input AND gate, a 2-input AND gate, and a 2-input OR gate. The logic gates, NOR, AND, and OR come in TTL and CMOS equivalents which can be found at Lees Electronic. This project is a simple egg timer with two settings: hard or soft boiled and comes with a reset function.
Parts and Tools
1x Breadboard (Lee’s Number: 10516)
1x 9V battery (Lee’s Number: 8775, or 16123)
NOTE: THIS CIRCUIT CAN ALSO WORK USING 5V POWER. DO NOT EXCEED 9V BECAUSE IT MAY DAMAGE THE IC CHIPS
1x 9V battery holder (Lee’s Number: 657 or 6538 or 653)
Solid hook-up wire (Lee’s Number: 2249)
Jumper Wire (Lee’s Number: 10318 or 21805)
Alligator Test Leads (Lee’s Number: 690)
3x Tactile Switches (Lee’s Number: 31241 or 31242)
1x NE555 Timer (Lee’s Number: 7307)
1x 12-bit ripple counter CMOS 4040 (Lee’s Number: 7210)
1x Dual Quad input AND gate CMOS 4082 (Lee’s Number: 7230)
1x Quad 2-input AND gate CMOS 4081 (Lee’s Number: 7229)
2x Quad 2-input NOR gate CMOS 4001 or 74HC02 (Lee’s Number: 7188 or 71692)
1x Quad 2-Input OR gate 74HC32 (Lee’s Number: 71702)
3x 1k OHM resistors ¼ watt (Lee’s Number: 9190)
2x 150k OHM resistors ¼ watt (Lee’s Number: 91527)
1x 10nF (0.01UF) capacitor (Lee’s Number: 8180)
1x 4.7UF Capacitor (Lee’s Number: 85)
1x 1N4001 Diode (Lee’s Number: 796)
1x Buzzer 3-24V DC Continuous (Lee’s Number: 4135)”