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adjustable 2 digit 7-segment counter

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DuffyHimself

New Member
Hello. I am doing a project where i have to make a circuit that will allow me to adjust two 7-segment displays with two buttons. One button for increasing the number on the connected displays and one button for decreasing the number.

What components do i need and how do they need to be connected?

I don't know how to use programmable chips so don't suggest that please.

Any help will be appreciated :)
 

MrDEB

Well-Known Member
heres a start that should help

first look at the cd4029 ic
then look at these two circuits
the power supply circuit HAS the circuit your wanting to build. just figure out what to eliminate and combine from the two circuits.
pretty simple
Simple Digital Counter - doc00021


Electronics for You-Circuit Lab- Free and tested circuit diagrams-15-Step Digital Power Supply
good luck.
when you think you have a design then come on this forum and ask.
the great people on here don't design from the ground up but will help in avoiding smoke creating mistakes.
 

DuffyHimself

New Member
Thanks for replying. But i am not sure you have understood what i wanted to make.

The two buttons has to adjust the 7-segment display only by pressing the buttons. So if i press the up button it only goes 1 higher for every time i click it, and the same with the down button.

Alternatively it could work so that as long as i hold down the up button it counts up, and when i hold the down button it counts down, but when i'm not clicking any of the buttons it needs to stay at the number it's at.

Can i use the CD4029 ic for that?
 

ericgibbs

Well-Known Member
Most Helpful Member
Thanks for replying. But i am not sure you have understood what i wanted to make.

The two buttons has to adjust the 7-segment display only by pressing the buttons. So if i press the up button it only goes 1 higher for every time i click it, and the same with the down button.

Alternatively it could work so that as long as i hold down the up button it counts up, and when i hold the down button it counts down, but when i'm not clicking any of the buttons it needs to stay at the number it's at.

Can i use the CD4029 ic for that?
hi,
If you want to drive 7seg displays from the up/down counter look at the CD40110 ic.
Its an up/dwn counter with inbuilt display drivers.

Datasheet Archive - Free Datasheet Search Engine - PDF Datasheets - Data Sheet - Datasheet - Application Note - Free Texas Instruments Samples

OK.?
 

Sceadwian

Banned
Woops, sorry Eric =) Great minds think alike, apparently so do ours =\
 

DuffyHimself

New Member
Hello again.
First i have a question. When the counter is on 9 and it goes one up does it go to 0 and sends a signal to carry, or does it keep counting to 15 and sends signal to carry when it resets at 16?

When I've got this set up I need to change the seven segment code from the outputs of the two CD40110, into digital code, so I can connect it to a DAC to get a voltage that changes up or down with the counter. Can i do this? Or do i need to get an IC similar to CD40110, that has a digital output instead of 7-segment?
 

Sceadwian

Banned
Do you still need the display? If not just use an 8 bit up/down counter. If you want the display AND the digital output it's a little more complicated because the CD40110 isn't smart enough to be able to set itself to 255 if you decrement from 0. I'm not sure how you would go about it, at that point I would use a micro controller as all these problems go away because it can all be done in code on a single chip.
 
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DuffyHimself

New Member
I can't code so that isn't an option.

I'm basically doing a college exam project where we gotta have 2 sets of displays.
We will use an op-amp to compare the output from the two DAC converters that will be connected to the display sets. Both display sets will be done in the way mentioned in this thread. So we need two buttons for each set (up down) that will change to number on the displays and also change the digital input to the DAC converters. To make things simple we can manage with a 4-bit code, so the displays can go between 0 and 15.

The digital input to the DAC converters doesn't have to come from 7-segment code, but with the CD40110 IC there isn't any digital output.
 
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DuffyHimself

New Member
My classmate has found another IC we could possibly use, but we aren't sure.

The IC is 74F193 (http://www.fairchildsemi.com/ds/74/74F193.pdf)
As far as we can understand it can do the same manual up down count as the CD40110 and it gives a digital output rather than a 7-segment code - but it says that it will change to 0 (and send signal through carry) after 15, and not after 9 as we want it to. Is it possible to make it change after 9 instead of after 15?
 

ericgibbs

Well-Known Member
Most Helpful Member
My classmate has found another IC we could possibly use, but we aren't sure.

The IC is 74F193 (http://www.fairchildsemi.com/ds/74/74F193.pdf)
As far as we can understand it can do the same manual up down count as the CD40110 and it gives a digital output rather than a 7-segment code - but it says that it will change to 0 (and send signal through carry) after 15, and not after 9 as we want it to. Is it possible to make it change after 9 instead of after 15?
Use a 74LS190 or 74LS192 or HEF40192 BCD not Binary.
 

Sceadwian

Banned
Duffy, ANYONE can code in basic. They taught basic in my 5th grade class. With a list of functions you can use and 10 minutes of studying a basic programming primer you can have working code, don't sell yourself short and be stubborn about a perfect solution because you're reticent to try out new things.
 

DuffyHimself

New Member
Hello again.
We decided to go with the 74LS192. But now we can't get it to work.
We have connected it like this:
Pins:
1, 9, 10, 12, 13, 14, 15 : nothing
2, 3, 6 & 7: BCD to 7 segment converter (74LS47)
4: Up counter button
5: Down counter button
8: Ground
11: Positive input
16: Positive input

Is this correct?

Also do i read the datasheet correctly, in thinking that the digital output goes one up or down every time one of the button inputs changes from high to low voltage? And that the other button input has to be on high when this change occurs?

Also if it needs to be done like just mentioned i have another question.
We have a button with a spring in it, so that when you push it down it closes the circuit, and then when u lift the finger it breaks the connection. But if we need the other input to be on positive we need the buttons to break the connection rather than closing it. Is it possible to do this with the buttons we have? Or do we need to get some buttons that break the circuit when pressed? And if so, what are they called?
 

duffy

Well-Known Member
Wait - I'm Duffy himself, how can you be Duffy yourself?
 
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MrDEB

Well-Known Member
your circuit is wrong

11 is the load pin so when the dip switches connected to pins 9,10,1,15 are preset then the value gets loaded into the 74192 when pin 11 is grounded. if building this I and don't need the programable inputs then connect a 1k resistor to pullup pin 11.
pin 4 is the down pin.
pin 5 is the up pin.
I see your post refering to a variable voltage.
did you even look at the 15 step variable voltage circuit?
Electronics for You-Circuit Lab- Free and tested circuit diagrams-15-Step Digital Power Supply
this circuit has BCD outputs!!
must be young high school kids or ?? that want somethig easy.
how much easier than the link I gave you??
its exactly what you want as per your description
just add the 7447 and the 7 segment display or better yet the 4511
it has 2 latch/decoder/drivers per chip
 

DuffyHimself

New Member
Thanks for the answer, but i went ahead with my original design and solved the problem by making the circuit in a program called Tina 8.0.
But now i'm a bit lost on how to connect the DA converters. I've connected them like this so far:



And now i don't know how to connect the 4 remaining pins on each of them. The analogue output (i assume this is the one called A) from each of the DAC's, has to be connected to the OP AMP to compare them. When the bottom DAC gives a higher output than the upper, the lamp after the DAC has to light up.

edit. oops, posted wrong picture
 
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