Simple Clock

Hello all I have a project in which I need to "build" a clock which counts to 24 (all I really need to do is correctly draw the diagram), I am able to simulate the count in binary but when I attach the binary input into the seven sigment the count doesnt come out right; after nine the seven sigment starts to make illedgible figures.

I believe what I need is how to convert my binary inputs into BCD by using electronic components. I know that in reality there are binary to BCD decoders but I am not able to use one of these in my project, so I need to build one from parts. Can some one help me with how to do this. I have searched extensively on the internet, but thusfar come up with nothing.

Thanks in anticipation

Fred

Binary to BCD

It sounds like your assignment is to draw a schematic of a bin. to bcd decoder.
What kind of parts are you allowed to use ? do you have to use discrete logic gates ? The easiest way I can think of is to use a ROM.

You could use BCD counters, a 7490 series device would be a good place to start. It can be configured as divide by 2, 5 or 10.

Hello, thanks for replying. Im not allowed to use ROM. Im using the program Electronics Workbench (if youre familiar with it), so I use a binary counter using J-K flip flops and I want to conver the five bit binary to a BCD with logic gates and flip flops, shift register, adders, etc.

I think you were right in saying I need to draw a "schematic of a bin. to bcd decoder". But dont know the inner workings of a binary to BCD decoder, any ideas?

Fredisdead said:

Hello, thanks for replying. Im not allowed to use ROM. Im using the program Electronics Workbench (if youre familiar with it), so I use a binary counter using J-K flip flops and I want to conver the five bit binary to a BCD with logic gates and flip flops, shift register, adders, etc.

I think you were right in saying I need to draw a "schematic of a bin. to bcd decoder". But dont know the inner workings of a binary to BCD decoder, any ideas?

Click to expand...

Are you sure your not being required to just design a BCD counter with your J-K FFs? It's a pretty simple addition (some gates driving the reset pins) to make a 4 bit binary counter 'reset' on the tenth clock pulse back to zero, therby becoming a BCD counter.

Lefty

Binary to BCD converter.

Hi Fred,

Here's one, and it will work up to 25, not higher.

on1aag.