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HCF4017BE Decade Counter with 10 Decoded Outputs
On reaching “9” again returns to “0” and so 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 datashert attachment. 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.
HCFBE Datasheet, PDF – Alldatasheet
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 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. All suggestions are hearty welcoming It has active HIGH pin Yes, the in the design is set to count to N and recycle so it waits till it gets to N regardless of where the pulses clock is from. Real quick something that could maybe work is using a chip like a in a missing pulse configuration. You would need to calculate the time approximately between rings Pulses on ring signal and set things up as a retriggerable one shot.
The output would be low and on rings go high. The output would remain high till the time between pulses exceeded the RC time set and the output would go low. Maybe use that with a gate for pin 15 Reset? Boncuk New Member Feb 25, Hi, I modified the circuit to automatically reset independent of the number of rings. The monostable is initiated by the first positive clock edge at pin 14 CLK. Q1 through Q4 are ORed with diodes. This is one example of why I design with a microcontroller.
An 8 pin PIC chip and 6 components is all you need.
Boncuk, if i have not understand wrongly, the 4 doides connected from 2nd to 5th out puts are not important, since as he said if the ring discontinues in between, then on of the input would be high and you will never get a reset output. A much better hcf40117be simpler design is to have two timing circuits that detect ringing for say 10 seconds but not longer than 20 seconds. The result energises a relay for 60 seconds.
This can all be done with a 74c Boncuk New Member Feb 26, All suggestions are very valuable. See my attached link ” 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. So Quasi length 0. But this will introduce Delay time 1. But in practice we can neglect it as not affecting our project aim in any way. I ratasheet this is the most perfect circuit. The big problem with your circuit is this: It will activate the output for any number of rings above 5.
My circuit only accepts a coded number of rings. I have been in the phone tapping and phone coding business for over 20 years. dataheet
STMicroelectronics HCFBE – PDF Datasheet – Series In Stock |
I developed the Infinity Bug over 15 years ago using a coded ring. Your circuit is quite useless.
Maybe off topic but I always wondered about this part: The receiving phone can pick up the end of half a ring and this will not be detected by the caller, but the circuit will see it as a full ring.
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