Hi, I'm working on a project in which I need to create an 8-bit adder with two cascaded 74LS193s, so that when it reaches 255 it starts subtracting, creating some kind of triangular waveform by steps. It works well in the first part of the waveform but in the remaining part it has a sudden jump from 0 to 255. The waveform is generated based on a clock signal provided by the 555. I would greatly appreciate your help.

 

I would use 74LS191 instead of 74LS193 because it has UP/DOWN control input.

 

I would use 74LS191 instead of 74LS193 because it has UP/DOWN control input.

how i can do wit 8 bits?

 

Then entire schematic would be useful. It appears it is cutoff in your post.

 

Then entire schematic would be useful. It appears it is cutoff in your post.

it is cut because after the adder there is a DAC8080, to make a D/A source, if you want i can upload the entire circuit

 

Please upload the entire circuit - it might be helpful to some and you won't get changed for the disk space : -)

 

Hi, I'm working on a project in which I need to create an 8-bit adder with two cascaded 74LS193s, so that when it reaches 255 it starts subtracting, creating some kind of triangular waveform by steps. It works well in the first part of the waveform but in the remaining part it has a sudden jump from 0 to 255. The waveform is generated based on a clock signal provided by the 555. I would greatly appreciate your help. View attachment 291956

Why do you need to use two cascaded 74LS193s? Is that a requirement of the assignment?

What is it that you are adding and subtracting?

 

Please upload the entire circuit - it might be helpful to some and you won't get changed for the disk space : -)

For shure, theres is a screen shot of that, and the proteus File

 

Why do you need to use two cascaded 74LS193s? Is that a requirement of the assignment?

What is it that you are adding and subtracting?

yes, i need to to do it physically and in mi city i only found the 74ls193. And i am adding and subtracting from 0 to 255 and 255 to 0 according to a clock based on the 555.

 

yes, i need to to do it physically and in mi city i only found the 74ls193. And i am adding and subtracting from 0 to 255 and 255 to 0 according to a clock based on the 555.

Hello there, in case of any one needs the cicuit here is, i finally solve it by changing the 7 AND door to an a 8 And door that includes the first bit, the combination at the dip switchis (in the numbering on the left side):

up:
1 off
2 on
3 on
4on
down:
1on
2 off
3 on
4on
both:
1on
2 on
3 off
4 off
Note ( i am using proteus 8.13)

 

If anyone is interested in whether the circuit works, I have attached photographs of the setup and the generated signal. For the 8-input AND gate, I used a CD4068 IC, using pin number 1 (non-inverted). Additionally, I used a TL074 as a current-to-voltage converter. One additional note is that the pin order on the DIP switch was reversed for some reason (so on and off were switched), and I recommend using 4400 uF capacitors (in my case, two 2200 uF capacitors in parallel).
Circuit assembly.

Upward curve.

Downward curve.

Mixed curve. There's a part that I really don't understand: why is the frequency so high in this section? And why is the voltage so small?

But it´s working, so if anyone is interested on that can email me.

 

Hello there, in case of any one needs the cicuit here is, i finally solve it by changing the 7 AND door to an a 8 And door that includes the first bit, the combination at the dip switchis (in the numbering on the left side):

Hola Juan,
"Puerta" can be translated to "door" or "gate".
In English, we say "AND gate", not "AND door" for "puerta lógica" .

 

Hola Juan,
"Puerta" can be translated to "door" or "gate".
In English, we say "AND gate", not "AND door" for "puerta lógica" .

oooooh thank you so much