Mod 5 counter

D

digital_geek

New Member

• Jul 8, 2005

• #1

I am trying to build a mod-5 counter and need a schematic for it. Any help it would be appreciated. If possible a schematic using all gates not IC's.

 

P

Parag0n

New Member

• Jul 8, 2005

• #2

ever get the feeling someone wants you to do their homework for them?

 

U

upand_at_them

Active Member

• Jul 8, 2005

• #3

Yup. All the time.

 

3

_3iMaJ

New Member

• Jul 8, 2005

• #4

I'll tell you how to do it but I won't give you the schematic.

You need either a decade counter or a 4 bit counter, either will work. Just use some logic to set the clear flag when you the number 5 shows up on the counter.

You can probably do it with less than 5 gates, its very simple.

 

3

_3iMaJ

New Member

• Jul 8, 2005

• #5

I just realized a mistake above, since its a mod 5 counter, you want it to clock the reset at 5, but it will technically count to "5" but only for a split second. Just one of the many problems of being in the real world.

Sorry about that.

 

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upand_at_them

Active Member

• Jul 8, 2005

• #6

I'd do it with a small, cheap PIC. But the homework assignment won't allow that.

Mike

 

3

_3iMaJ

New Member

• Jul 8, 2005

• #7

You could build one with a few FFs, but I guess it depends how complicated you want it to get.

 

jbeng

Member

• Jul 10, 2005

• #8

A 7490 is constructed from a divide-by-2 and a divide-by-5 counter. Download the datasheet and look for the internal logic diagram. It details how the gates are connected internally to achieve these functions. Also, the 74hc390 is similar, but it has two div-by-2 and div-by-5 systems inside.
JB