DIY Discrete Logic LED Countdown Timer -- Episode 509

This digital countdown timer displays remaining time set for a deadline/event. The USP of this project is that it is built without using any microcontroller unit. So, It is about going through a fair journey to hardcore digital electronics involving concepts of clock, counter, and digital logic design.

Bill of Material:

Product Name	Manufacturer	Quantity	Buy Now
CRYSTAL, 32.768KHZ, 12.5PF, CYLINDER	ABRACON	1862377	Buy Now
7 Segment LED Display, Mechanically Rugged, Red, 20 mA, 8 V, 55.5 mcd, 1, 56.9 mm	KINGBRIGHT	1168637	Buy Now
Ripple Carry Binary / Divider, CD4000 Family, 24 MHz, 3 V to 18 V, DIP-16	TEXAS INSTRUMENTS	3119758	Buy Now
Logic IC, OR Gate, Quad, 8 Inputs, 14 Pins, DIP, 7432	TEXAS INSTRUMENTS	3006469	Buy Now
BCD to 7 Segment Decoder / Driver / Latch, 1 Gate, 4 Input, 7 Output, 6.8 mA, 3 V to 18 V, DIP-16	TEXAS INSTRUMENTS	3119855	Buy Now
Binary / BCD Up / Down Counter, 11 MHz, 3 V to 18 V, DIP-16	TEXAS INSTRUMENTS	3006272	Buy Now
Flip-Flop, Complementary Output, Positive Edge, CD4013, D, 45 ns, 12 MHz, 6.8 mA, DIP	TEXAS INSTRUMENTS	3119947	Buy Now
Logic IC, AND Gate, Triple, 3 Inputs, 14 Pins, DIP, 74LS11	TEXAS INSTRUMENTS	3120530	Buy Now