Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

7 segment display

Status
Not open for further replies.

zattara13

New Member
i am working on a simple project. it involvs a 4 bit full adder (7483) to light up a 7 segment display by using a bcd to 7 segment display converter (7447). i managed to display numbers 0 till 9 but at 10 i wanted for it to display 1 and the decimal will light up indicating the 'tens'. example ... 8; 9; 1.; 2.; 3.; ...

how can i do that? any suggestions? 10x
 

saturn1bguy

New Member
i am working on a simple project. it involvs a 4 bit full adder (7483) to light up a 7 segment display by using a bcd to 7 segment display converter (7447). i managed to display numbers 0 till 9 but at 10 i wanted for it to display 1 and the decimal will light up indicating the 'tens'. example ... 8; 9; 1.; 2.; 3.;

It seems to me a better sequence would be 8, 9, .0, .1, .2, otherwise you're missing either ten or eleven (can't tell).

The carry out (C4) should be used to light up the decimal point (using appropriate buffering, etc) for the tens position...
 

Boncuk

New Member
Hi zatarra13,

you can't display '10' using the 7483. It is a binary full adder, meaning its counting sequence ranges from zero to fifteen. The carry output is only active if the count exceeds 15, so it can't be used to indicate '10'.

However the numbers 0 through 15 should be displayed as normal numeric values followed by the letters A trough F representing the values 10 through 15.

The 7447 is not quite suitable because it displays symbols instead of letters.
Try the 7448 which should display the correct values and letters.

Boncuk
 

saturn1bguy

New Member
It involves a 4 bit full adder (7483) to light up a 7 segment display by using a bcd to 7 segment display converter (7447)

This is still a bit confusing as you mention using full (binary) adders but are using BCD-to-Seven Segment decoders. One can build BCD adders out of full adders, or just use the 74F583, which is a BCD adder. You sort of need to choose one or the other approach, BCD or binary.
 

Boncuk

New Member
Or use a 74LS90, a decade counter. I has a carry out pin active at overflow (carry out) , meaning at '10'.

Use the carry out signal and 'AND' it to display '1.'

I don't know if this will work, since the counter jumps to zero at overflow. So it will probably result in '0.'

Boncuk
 

saturn1bguy

New Member
Or use a 74LS90, a decade counter. I has a carry out pin active at overflow (carry out) , meaning at '10'.

The OP never mentioned counters, but he's still using full adders, as you pointed out, Boncuk, with BCD decoders, so potentially he could get some really funky results. (Is he inputting binary or BCD digits to his adders, etc.)

So, it still seems to me he needs to define what number base he's going to use, and stick with it. But who knows what the OP is really up to...
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top