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02/24/06 10:57
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#110661 - Pressing 555 trigger SW continuously.
Hello all,
i connected the 555 in monostable state (previously discussed)
to achieve a varying time delay from (0 - 10 sec) and is working fine when tested with an LED.
In that circuit i could see the following:
1 sec delay has been set by the pot.
Then when i gave a trigger the LED glows for one sec and then go's OFF. Fine.
But,
when the trigger is continuously pressed without releasing it, the LED keeps on glowing, but not switching OFF after 1 Sec.
This creates problem in my application.
What my application need is,
The LED should be ON only for the time set by the pot (the time set could be from 0 to 1 sec also) irrespective of the switch(trigger) being depressed.
I would like to know whether it can be achieved by any means.
Also, i didnt use any debounce circuit or debounce IC in the trigger i/p. will this could be a cause to the problem.

suggestions please.

suresh.





List of 39 messages in thread
TopicAuthorDate
Pressing 555 trigger SW continuously.            01/01/70 00:00      
   Again            01/01/70 00:00      
   capacitor couple it.            01/01/70 00:00      
      Re: cap coupling            01/01/70 00:00      
         Look up the internal block diagram            01/01/70 00:00      
            Read the Data Sheet!!            01/01/70 00:00      
      got the o/p            01/01/70 00:00      
         Satisfaction            01/01/70 00:00      
            Thanku steve            01/01/70 00:00      
         Not enough            01/01/70 00:00      
            alternatives ?            01/01/70 00:00      
               Remedy            01/01/70 00:00      
                  remedy?            01/01/70 00:00      
                     Alternatives            01/01/70 00:00      
                  BC550 & diodes            01/01/70 00:00      
                     Try it by yourself, it's simple!            01/01/70 00:00      
                        analysis results            01/01/70 00:00      
                           Analysis            01/01/70 00:00      
                              Thank you            01/01/70 00:00      
                              after the set delay Time            01/01/70 00:00      
                                 Enhanced debouncing            01/01/70 00:00      
                                    What do you think about it, Suresh?            01/01/70 00:00      
   why the neqw thread            01/01/70 00:00      
      reply            01/01/70 00:00      
         Read the Data Sheet!!            01/01/70 00:00      
   kalpak dabir            01/01/70 00:00      
   Have you considered using a 74121?            01/01/70 00:00      
      74121 versus CMOS555            01/01/70 00:00      
      74121 fine for short period delays?            01/01/70 00:00      
         No debounce needed???            01/01/70 00:00      
            Schmitt trigger operation?            01/01/70 00:00      
               Transition times of input signal            01/01/70 00:00      
                  controlling noise related issues            01/01/70 00:00      
                     Schmitt-trigger operation            01/01/70 00:00      
                      CD 4541BC = Alternative for ICM 7555?            01/01/70 00:00      
                        Do you really need to build it?            01/01/70 00:00      
                           Yes.            01/01/70 00:00      
                              try try try again            01/01/70 00:00      
                                 a sign of confidence            01/01/70 00:00      

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