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Author Topic: Missing pulse detector help  (Read 5900 times)
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hogar
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« on: December 10, 2008, 08:01:52 20:01 »

   
Help me with detectors pulse from 4 independent sources for 2-4 seconds with a beep and automatically reset when the pulses repeat again
If someone has an idea ....

Thanks in advance
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Parmin
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« Reply #1 on: December 10, 2008, 10:07:30 22:07 »

use watchdog timer on a PIC, do a CLRWDT on pulse and a beep when WDT trip.
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hogar
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« Reply #2 on: December 10, 2008, 11:58:07 23:58 »

   
Thanks, but I'm not good with PIC need something "older" or a little more help,actually a lot of help
   
If you have the will and time....
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itp
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« Reply #3 on: December 11, 2008, 04:47:47 04:47 »

Hi hogar,

If I understood your problem correctly , you can use a re-trigger able mono-shot with 2 to 4 Sec delay. Re-trigger this mono shot by the pulses in your problem. If this trigger pulses misses  the mono-shot will no longer will get trigger and it will change the state. This state of the mono-shot can be used to trigger your alarm circuit. Hope I am clear.
Regards
Itp
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jzaghal
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« Reply #4 on: December 11, 2008, 12:27:53 12:27 »

Hi,

Try investigating the popular 555 Timer. It is sometimes used as a Missing Pulse Detector.

Hope this helps.

Bye.
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hogar
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« Reply #5 on: December 11, 2008, 07:15:54 19:15 »

I need the following:
If the pulses delayed more than 2-4 seconds to activate an alarm ,when a pulse re-establish that the alarm goes out, of course for 4-6  independent sources of pulses
Project need to monitor mixing granulated food with 4-6 components
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zuisti
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« Reply #6 on: December 11, 2008, 08:02:50 20:02 »

Hi;
I agree with Itp,
Simply use a "Dual retriggerable monostable multivibrator" type 74hc123 to sense two pulse (use two same ICs for 4 pulses and so on ... )

 Study the datasheet here:
http://www.nxp.com/acrobat_download/datasheets/74HC_HCT123_4.pdf

I think  it's possible to realize the circuit without any processor... it's a really "older" solution.
Good luck
zuisti
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Parmin
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« Reply #7 on: December 11, 2008, 10:27:19 22:27 »

Agree with ITP and zuisti

Definitely doable..
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hogar
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« Reply #8 on: December 11, 2008, 10:39:12 22:39 »

Thank you guys for advice!!!
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titi
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« Reply #9 on: December 12, 2008, 09:14:30 09:14 »

Hi,

This is an example with NE555 found in the good soft : 555 Etcetera,
 posted on sonsivri : http://www.sonsivri.com/forum/index.php?topic=5468.0

To calculate the value of R1 and C1 use the same soft.

Regards.
« Last Edit: December 12, 2008, 09:17:32 09:17 by titi » Logged
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