Digital circuits

yutikab · Oct 16, 2012

Hello friends,
I need an solution for an very silly query you may all consider,

I need to build a RING COUNTER using D-FLIP FLOP.. My problem is that am not able to make the connections on IC 7474 which is a DUAL TYPE D FF I require only one input out of the two.

I am building a 4-bit ring counter, what do i need to do with the unused pins like the 2nd input and output pins as well as the set reset pins of both the inputs.

Please help me out its URGENT.

ericgibbs · Oct 16, 2012

hi,
Look here.
https://technosains.com/RingCounter.htm

Note:
on the 7474 TTL type, unconnected/unused inputs will assume a High state.

The small circle on an input pin indicates that the pin is active Low, so the unused /CLR and /PRE pins will be High.

Ideally a pull up resistor should be connected to unused active Low pins.

OK.?

crutschow · Oct 16, 2012

If you need a four-bit ring counter can't you use the two flip-flops in each chip and do it with two chips?

MikeMl · Oct 16, 2012

yutikab said:
...Please help me out its URGENT.

When is the home work due?

I think the OP is asking what to do with the Set and Clr input pins, and possibly the unused Q and Qbar putput pins?

If all you do is hook Q to Din (and Qbar of the last flip-flop to D of the first flip-flop ) you will fail the homework assignment. (At least if I was grading it). You need to consider that the flip-flops can come up in random states, and some of those states will create a hazard where the cycle is shorter than the eight states you think you are going to get.

Roff · Oct 17, 2012

MikeMl said:
When is the home work due?

I think the OP is asking what to do with the Set and Clr input pins, and possibly the unused Q and Qbar putput pins?

If all you do is hook Q to Din (and Qbar of the last flip-flop to D of the first flip-flop ) you will fail the homework assignment. (At least if I was grading it). You need to consider that the flip-flops can come up in random states, and some of those states will create a hazard where the cycle is shorter than the eight states you think you are going to get.

There are two types of ring counters. You described a Johnson counter. The other type has the last Q (not Qbar) wrapped back to the D input on the 1st stage. (I just learned this is called an Overbeck counter.) We really don't know which kind the OP needs to design.

Digital circuits

yutikab

New Member

ericgibbs

Well-Known Member

crutschow

Well-Known Member

MikeMl

Well-Known Member

Roff

Well-Known Member

Similar threads

Digital circuits

yutikab

New Member

ericgibbs

Well-Known Member

crutschow

Well-Known Member

MikeMl

Well-Known Member

Roff

Well-Known Member

Similar threads

Privacy & Transparency

Privacy & Transparency