74LS47 w/ 7-seg display latching up?

[AllVol]

Uh.. because I have another digit there - so there's 2 7490s.

I'm afraid you or I one doesn't understand.

You're wanting to count a two digit number, like 60, right?

The 7490 counter counts 0 - 9 continually. The 744(x) usually blanks the first zero, then counts 1 - 0, displaying on the seven-segment. If there are more numbers incoming from the 7490, it automatically carries over to the next 744(x), which displays it's digit. You can continues this string, using only one counter, on and on ad infinitum, or until you run out of time, space or money.

 

[AllVol]

TI lies! Here is my datasheet, showing all segments high except for "g", which is low displaying a "zero"

I tried to edit my other reply to save bandwidth, but I goofed up.

See below, which might shed further light on this enlightening subject.

 

[littletransistor]

I'm afraid you or I one doesn't understand.

You're wanting to count a two digit number, like 60, right?

The 7490 counter counts 0 - 9 continually. The 744(x) usually blanks the first zero, then counts 1 - 0, displaying on the seven-segment. If there are more numbers incoming from the 7490, it automatically carries over to the next 744(x), which displays it's digit. You can continues this string, using only one counter, on and on ad infinitum, or until you run out of time, space or money.

Yes - I did want to count a 2-digit number, right up to the 0 - 59. That's why I'm making it with 2 7490s, one with the decade, another modulo-6, and with the corresponding 2 7447s to drive the digits.

Strange as it seems, the 2nd digit (the 10s) are frizzled. Some of the segments are missing. However when I trace the QA-QD - the BCDs are correct. I checked the 7447 as well - it's working. What else could it be?

 

[Boncuk]

Yours shows the state of each segment... on or off.

The other sheet gives the condition that results in the segments state.

Confusin', ain't it.

State or condition doesn't mean a difference. Knowing that the LS47 is an open collector driver makes sense to me. Open collector logic is on = low (negative logic)

A small correction here: It's the LS248 decoding numbers displaying tails.

LS48 ist just the equivalent for the LS47, this time with positive logic, on = high.

Boncuk

 

[Mikebits]

Strange as it seems, the 2nd digit (the 10s) are frizzled. Some of the segments are missing. However when I trace the QA-QD - the BCDs are correct. I checked the 7447 as well - it's working. What else could it be?

Maybe something burned up when you ran it without I limit resistors?

 

[Mikebits]

TI lies! Here is my datasheet, showing all segments high except for "g", which is low displaying a "zero"

This should clarify. Here are the outputs for the 47 and 48.

 

[AllVol]

And, here's more from the data sheet:

 

[littletransistor]

Maybe something burned up when you ran it without I limit resistors?

Ah, got the 2nd digit working. I forgot to connect the last QD in the 74LS90 to the last QD in the 74LS47. Haha...

 

[Boncuk]

Ah, got the 2nd digit working. I forgot to connect the last QD in the 74LS90 to the last QD in the 74LS47. Haha...

Watch it closely! It's the beginning of alzheimer.

 

[davidbball13]

it is a lot easer if you use a 4026 for this it is one IC and only needs a clock. you can easly add more # with the divide by 10 pin