Hello everybody,

I have a project which is to make a system that counts backwards from 9 to 0 (9 - 8 - 7 ... 0 etc.) with 1 sec periods. I can't use arduino or coding stuff so I just need to use some integrated circuits, so far I though to make a system with 74ls47(decoder), 555 (timer) and I should find an integrate which is able to count down that might be 73hc192 or 73hc193? can't decide which one to use and if I use one can't really decide how to connect them to each other.

Also when I am connecting these integrates, the clock leg should be connected to 555 right ? since it is the one giving away the # signal ?. Coulnd't really find detailed info on backward counters so also some general info would be great, thanks beforehand!.

 

Hello,

I think you mean the 74HCT192 and 74HCT193 in stead of the 73's.
Both are up/down counters.
The 192 is a BCD and the 193 is binairy.

Bertus

 

Why don't you use 4-bit ripple down counter that starts from 9 ? You'll require 4 negative edge triggered JK flipflops and 555 IC for clock. You can search on youtube for more details.

 

Hello,

I think you mean the 74HCT192 and 74HCT193 in stead of the 73's.
Both are up/down counters.
The 192 is a BCD and the 193 is binairy.

Bertus

Yep I meant to write 74, but which one is to be used and why ? both of them have the same datasheet so I guess it doesn't really matter ?

 

Why don't you use 4-bit ripple down counter that starts from 9 ? You'll require 4 negative edge triggered JK flipflops and 555 IC for clock. You can search on youtube for more details.

Yeah I also though to use FF with 555IC but I guess using a integrated circuit would be better and easier I guess ?

 

For your project either of SN54192, SN54193, SN54LS192, SN54LS193, would work just fine and you really only need the 192 chip for count down 9 to 0. The 555 can be used as your clock and the 7447 as your seven segment display driver. This also sounds like school assignment work. You have a clock chip, the 555 timer, followed by a synchronous 4 bit up/dn counter followed by a decoder driver for your display. The 74192/74193 data sheet I linked to explains everything you need to know.

Ron

 

For your project either of SN54192, SN54193, SN54LS192, SN54LS193, would work just fine and you really only need the 192 chip for count down 9 to 0. The 555 can be used as your clock and the 7447 as your seven segment display driver. This also sounds like school assignment work. You have a clock chip, the 555 timer, followed by a synchronous 4 bit up/dn counter followed by a decoder driver for your display. The 74192/74193 data sheet I linked to explains everything you need to know.

Ron

Yeah it is exatcly as you said, so right now I have the system works fine while counting up from 0 to 9, how can I reverse it, do you know which connections should change ?

I have changed the 4th and 5th legs of those connections (one is down and the other is up). Other than those is there anything needs to change ? Bcs when I change those connections it doesn't count backwards just stays at 0. But as I said the normal counting is just fine.

Alsi how can I alter the counting speed. Thanks in advance !!

 

Your clock in goes to either the Up or Down input pin while holding the other (unused) pin at a logic high. Page 5 of the data sheet I linked to shows the count sequence clearly.

Ron

 

Ok, I got to do it, Thank you very much!!!