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Up/Down counters using 74LS193

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lespotter

New Member
Hi,

I have managed to get my counter to count up to 10 in units and then a second counter to count up in tens. I am trying to get it to count down when asked.

The count up is currently running from a signal source and the count down strapped to Vcc whilst counting up. i have tried putting a signal to one or both by removing the source signal and just using switches connected to Vcc but this does not work. Could anyone give me some advice please.

Thank you in anticipation

Les
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi,

I have managed to get my counter to count up to 10 in units and then a second counter to count up in tens. I am trying to get it to count down when asked.

The count up is currently running from a signal source and the count down strapped to Vcc whilst counting up. i have tried putting a signal to one or both by removing the source signal and just using switches connected to Vcc but this does not work. Could anyone give me some advice please.

Thank you in anticipation

Les
hi Les,
On the inputs do have a pullup or pulldown resistor also switches can be noisy, may need debouncing.

A simple diagram would help.
 

lespotter

New Member
Resistors

Hi Eric,

Heres the circuit as you see i have no resistors in it but this is only in the up counting. I know if i swap the inputs to up and down i can get a down counter but how do i get them to work together ie


1,2,3,4,5,4,3,4,5,6,5,6,5,6,7,8 etc

Regards

Les

:confused:
 

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ccurtis

Well-Known Member
In case you don't know it, a couple of 74LS192 decade counters would do the job without any decoding logic, by simply connecting the terminal count outputs of one counter to the up and down clock inputs of the other.
 

lespotter

New Member
74LS192's

Hi CCurtis,

Thank you for that snippet of information. Do you mean connect the BO and CO outputs to the up and down of the second one?

Regards

Les
 

ccurtis

Well-Known Member
Thank you for that snippet of information. Do you mean connect the BO and CO outputs to the up and down of the second one?
Yes, that's it. Connect the CARRY and BORROW outputs
of one device to the COUNT UP and COUNT
DOWN inputs, respectively, of the next device. Regards.
 
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