

Simple Quiz Display
Here is a basic project “Simple Quiz Display” using two different TTL ICs. Simple quiz display indicate which of the switch is pressed first among connected switch (i.e. four) by glowing its corresponding LED, where rest of LEDs is remains off.
Circuit Description
The entire circuit of simple quiz display is build and fabricated around two TTL IC. IC1 is BCD to decimal decoder (7445) where IC2 is Dual 4-input NAND gate (7420). The four push-to-on switch SW1 through SW4 is connected to pin 2, 3, 6 and 7 of IC1 respectively. The corresponding output is taken from pin 9, 10, 15 and 16 by connecting LEDs. SW5 is used to reset the quiz display circuit.
PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon)
R1 – R4, R9 = 1 KΩ
R5 – R8 = 680 Ω
Semiconductors
IC1 = 7445 (BCD to decimal decoder)
IC2 = 7420 (Dual 4 – input NAND gate)
LED1 – LED4 = four different color LEDs
Miscellaneous
SW1 – SW5 = Push-To-On-Switch
why do we need to convert BCD to decimal in this circuit?
how does the nand gate function here??
Hey Please Reply Immediately I am Having Trouble Making The Board in Eagle for This Simple Quiz Display.
So if You Can Make The Board and Send it to me via Mail it Will be Appreciated.