(hcf4017be) decade counter with 10 decoded outputs

Thread Starter


Joined Dec 24, 2009
Look up the attached data sheet.

I have suffered one displeasing feature (most times useful) of this counter,
When the clock advances, decade counting also advances from 0 to 9 then 0 to 9 and so on.
That is at first LOW-to-HIGH clock edge "0" out is on, at second LOW-to-HIGH clock edge "1"
out is on, and so on. On reaching "9" again returns to "0" and so on.

Assume we manually switch off the counter supply at seventh LOW-to-HIGH clock edge "8" out is on.
But the problem is that when we power up the circuit again, the counter starts from out "9" not from
initial "0" when detecting first LOW-to-HIGH clock edge.

In most applications this is a good feature.

But look up other attachment.

Here I set up a telephone ring detector to turn on off-hook relay
for 60 sec (by 555 mono), when 4017 detects 5th ring as Clock input. That is five LOW-to-HIGH clock (ring)
edges detected, then when goes to "6" out the counter automatically reset by the arrangement shown in schematic.
All these are done to count exactly 5 rings.

These arrangements normally working fine. But what happened when someone wouldn't complete 5 rings (missed call) ?
That is before completing 5 rings he deliberately cut his phone. Let us assume he disconnect his phone on 2nd ring.
Upon this condition when he tries to redial and want to turn on relay on 5 rings, relay will turn on before 5 rings
that is on 3rd ring. This occurs because of the property of 4017 by which it keeps track of all past (before power up also)

Is there any counters exist that has no past tracking feature. If I would get such a counter I will add one relay
at the output of opto-coupler, which will close power up connection of my counter when first ring signal occurs.
Thus the counter starts in a fresh mood to count exact no.of rings.

All suggestions are hearty welcoming ..........

In schematic 4017N decoder is placed, but the one I used is HCF4017BE. It has active HIGH pin 13.



Joined Oct 2, 2009
No design should count (pun intended) on having a counter come up in a specific state after an interruption of power. Why do you think there is a Reset pin????


Joined Dec 20, 2007
A resistor and capacitor will perform a power-up reset.
A CD4017 is exactly the same as any other 4017 including Philips HCF4017. A 74HC4017 is very fast with a high output current and therefore is different.

Thread Starter


Joined Dec 24, 2009
Thanks everyone to bring attention to my problem * (hcf4017be) decade counter with 10 decoded outputs
* .All suggestions are very valuable.

See my attached link '4017' in first post.
Where I have made a slight change to fulfill my requirement ( I think this would be a simpler version than
all circuits presented by others here).

See the attachment in this last thread.

1.5 SEC is designed by R and C of 4093 to satisfy one telephone ringing interval. 74123 retriggerable mono shot is used here.
So Quasi length (0.33RC) of 74123 is selected a little higher than the sum of 1.5 & 1 sec.
Whenever there is no rings at input, Q/ output is logic HIGH which will reset 4017.
But this will introduce Delay time (1.5 SEC) between the last ring and RESET. But in practice we can neglect it as
not affecting our project aim in any way.

I think this is the most perfect circuit.
Design ------- Quasi length TAKEN 3.3 sec THEN C=100uF R=100K

If have any suggestions pls post.........



Joined Aug 28, 2009
Use 74HC123, not 74LS123. 74LS is not be guaranteed to work reliably with 4000 series.
At the speeds you are working with, 74HC will be fine.


Joined Feb 2, 2010
I'm not full sure, but I think there may be a little error in that schematic. When the clock advances pin 15 should be connected to the ground.

These arrangements normally working fine. But what happened when someone wouldn't complete 5 rings (missed call) ?
I would add a transistor with a capacitor (5-10 seconds delay) on each output from 1 to 5, and a simple transistor on the last output (6). The collectors will be connected to a relay coil, which makes the reset.