24 second shot clock using D Flip-Flop

[jhay_e03]

how can i make 24-second shot clock using D Flip-Flop?
any help please.
 

[homer]

is this a clocked D Flip-Flop?

[jhay_e03]

yes. do you have any idea?
pls anyone  there...pls help

[homer]

one more question, do you want the clock to recycle at 25 or freeze until the reset button is pushed?

*EDIT*
also, you didnt quite specify, do you want the schematics?

[jhay_e03]

like the 24-second shot clock in regular game. i can reset it to 24 seconds, and i can pause the clock then resume.

*EDIT*
also, you didnt quite specify, do you want the schematics?

i want the schematic too.

[homer]

ok, give me a day or two to review my labs. i need to relearn this stuff from about 6 years ago.

[jhay_e03]

oh really? you already know this?? cool...ok,ill wait for your reply.... thank you very much   

[homer]

upon reviewing my labs, i realized that we used JK flip flops. a D type should still work, but is it possible to use JK flip flops instead?

and one more question, if you have to use the D flip flop, you said it was clocked, can i assume that it also has a set and a reset feature?

[jhay_e03]

if you have to use the D flip flop, you said it was clocked, can i assume that it also has a set and a reset feature?

what is the use of set and reset in D-FF? can i ask if what software are you using to see the output of the circuit? because we are using MULTISIM to simulate a circuit. and i also trying  to get the equations needed to get the right output. i am using 6variables K-mapping. do you think, i am using the right way?

[homer]

what is the use of set and reset in D-FF?

the reset is exactly what it means, if the CLR on the flip flop receives a low, it will reset to 0, regarding the set, i have no idea as all of our sets go straight to +5V.

below is a schematic for a 0-99 continuous, recycling, counter. its messy, i made it in MS paint 

this setup will recycle at 99.  to get it to recycle at 24, you need to setup the NAND gates A+B inputs differently. if i remember correctly, you will need to set the TENS NAND gate A and B inputs to the B and A output of the flip flops. for the ONES NAND gate, you will need to set the A and B inputs to the A and C outputs of the flip flops. if you need the schematics for the 4 X 7476 flip flops just ask, for they are actually 4 separate flip flops just drawn as one box for simplicity.

can i ask if what software are you using to see the output of the circuit?

i never used any software, i always used the hardware.

and i also trying  to get the equations needed to get the right output

i have a chart. see below and yes, its another messy MS paint pic.

i am using 6variables K-mapping.

i have no idea what this means, is this something to do with the software?

*EDIT*

i will draw up some schematics for a self-stopping counter that will stop at 24 tomorrow.


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[jhay_e03]

what is the effect if i will use set and reset in D FF or not?

below is a schematic for a 0-99 continuous, recycling, counter

why 0-99? and not 99-0?

this setup will recycle at 99.  to get it to recycle at 24

why do we need to jump to 99 to get it recycle to 24? is it possible that after reset the count will jump directly to 24?

if you need the schematics for the 4 X 7476 flip flops just ask, for they are actually 4 separate flip flops just drawn as one box for simplicity.

can i see the schematic for 4x7476?

dude, your so kind... thank you for helping me.... 

[homer]

alright, im downloading MULTISIM to see if i can construct a 24-0 countdown timer. i have never had a lab where we had to pause the display and recycle it manually, so i will have to do a bit of tinkering.

[homer]

hmmm, so far i have been unsuccessful at even reproducing the same results i got when i actually wired the device. this leads me to believe i am leaving something out or configuring something wrong when i make the schematic in multisim. i will need a bit longer to figure out how to correctly use multisim.

[homer]

i have not been able to successfully get the timer to count down from 9-0. i need to know of a way to filter out the hexidecimal because my timer counts as follows...

F,E,D,C,B,A,9,8,7,6,5,4,3,2,1,0.

meanwhile here is a schematic of what i have so far. i am currently trying to configure only one display to start with.

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[jhay_e03]

if im not mistaken...in 9-0 down counter, we will use here the "don't care condition" to ignore the F-A.