circuit plan or design needed - tricky problem

[cole7011]

tricky circuit problems

Hi all,

im looking for a circuit design plan or pcb track pattern annotated, for a backward counting circuit from 9, the tricky part is the next need, i would like a push to break switch to be used, and when the button is pressed the count stops on the number it was at.

i have given thought to the use of BCD counting and or decade counting...

all are viable but not have yet resulted in a design plan

please help!!

with thanks'

Mcole

 

[jshroff]

bcd using pcb wizard

This is simple to do with a PIC or another microcontroller. Are you opposed to using a micro?

 

[cole7011]

im not opposed to using a pic, alltough i would prefer another method if possible rather then pic

 

[Borber]

You may use binary or decade counter with count up/down with preset/load. It can find 74 or 4000 series type.

 

[cole7011]

ok.. but how would i go about hold system.... and or putting the circuit together in the first place.... design layout etc

 

[VVV]

If you can find some of these oldies, try this circuit.
For schematic/ layout try using EAGLE, there is a free versionat www.cadsoftusa.com

 

[cole7011]

what about a design using livewire, crocodile tech or pcb wizard?

 

[VVV]

You can breadboard it any way you want, I do not see any problem. I suppose the clock will not be too high.
One problem to be aware of: if the circuit is allowed to count past zero, it will not start at 9 again, it will go to 15. If you need it to start at 9, we need to add a few more things.
Note that you can use the latch with another AND or NAND gate to simply gate the clock to the counter, in order to start or stop it. That is, if you cannot get that particlar counter and have to use another one that does not have an enable pin.