(HCF4017BE) DECADE COUNTER WITH 10 DECODED OUTPUTS

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vinod
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(HCF4017BE) DECADE COUNTER WITH 10 DECODED OUTPUTS

Post by vinod » Thu Feb 25, 2010 3:37 pm

Look up the attached data sheet.
http://www.scribd.com/doc/27482245

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.
http://www.scribd.com/doc/27482318

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)
activities.

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.
@VinodQuilon

SETEC_Astronomy
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Re: (HCF4017BE) DECADE COUNTER WITH 10 DECODED OUTPUTS

Post by SETEC_Astronomy » Thu Feb 25, 2010 4:02 pm

I would use a timer that is triggered by the ringing clock to reset the 4017 if there isn't another ring within a few seconds. If a few seconds pass with no ring you can assume there won't be one.

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Lenp
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Re: (HCF4017BE) DECADE COUNTER WITH 10 DECODED OUTPUTS

Post by Lenp » Tue Mar 02, 2010 7:58 pm

Timers, counters Yikes!
Why not use a simple microprocessor and it is done!

Ring count
Abandoned call reset
Hook switch timer
Status lights

.
.
.
All these features and more with a single chip and some simple interfacing.

Len
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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