Do you want it to count down seconds from 300 to 0? Or do you want it to display minutes and seconds?yes sir/mam
-For the accurate timebase, you could use a 32.768 Khz tuning fork with a 15 bit binary counter
-For the down counter you could use the 74193 but have to figure out the gating to pre-load 300 seconds. Since in binary this is 0001 0010 1100, you need 3 down counters.
-If you want a geeky project, you could directly display the binary representation and have the players to decode the binary values in addition to playing the game. But don't think your players would like to do that. So you would require to convert the raw binary count into a 3 digit BCD while also converting to the 60-count based seconds display
-Finally, the BCD value convert it to a 7 segment LED value.
Overall, I would say that you are looking at over 20 IC packages, if you would like to do it with SSI ICs.
5minutes or 1 minute will doDo you want it to count down seconds from 300 to 0? Or do you want it to display minutes and seconds?
I doubt that you need a very accurate time base unless it's a tournament and you need accurate results between sets of players.
Do you want one timer being stopped to start the other timer?
Why are you using LS193? They're expensive and power hungry compared to CMOS.
I think an Arduino Uno/Nano would be a better solution.
7 segment led display(the 555 --or-- double T --or-- even the digital RC oscillator would give you exact enough time base)
? what is your display
- single/double digital LED as for "there is yet time remaining" and "the time has passed"
- analog micrometer converting output count to voltage by DAC
- binary led display
- 7-seg led display
by Jake Hertz
by Steve Arar