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Kai Klaas
02/02/06 07:10
Read: 1327 times
Germany


 
#108974 - Need not to work unreliably
Responding to: Erik Malund's previous message
Erik said:
The monostable is about the bitchiest circuit there is. If someone turns on a light switch in timbuktu it might fire. I do everything I can to avoid using one shots 555/221? or whatever.

A counter and a decoder will perform stable, predicatble operation. With small uCs available for less than $1, why not make a stable circuit.

Hmm, monoshots and oscillators are equally susceptible against noise on the trigger line. But there's a simple cure: Shielding and filtering. Maybe you have suffered from miscontructions, where shielding and filtering was omitted? Especially engineers doing in digital (I don't mean you, please) tend to handle monoflops not adequately. This is just a problem with 74221: This chip alone is perfect refering to stability and phase noise, but on a board not bypassed properly, on a noisy ground and without proper individual supply voltage filtering all the great performance is lost.

Monoflops I use, get always an RC-filter in the supply line. Additonally, I use monoflops which don't produce much noise by themselves, means I prefer the CMOS-555 instead of bipolar 555 for instance.

Kai

List of 57 messages in thread
TopicAuthorDate
Circuit for dispensing unit      Suresh R      01/31/06 05:09      
   1.1 sec monoshot      Abhishek Singh      01/31/06 09:43      
      this thread is apin off from an earlier      Terry Lingle      01/31/06 13:07      
         yes      Steve M. Taylor      01/31/06 13:55      
         timing circuit      Suresh R      02/01/06 04:17      
   Monostable      Andy Neil      01/31/06 12:08      
   Yes.      Steve M. Taylor      01/31/06 13:06      
   Hello All      Suresh R      01/31/06 22:23      
      Description of the "Dispensing Unit"      Andy Neil      02/01/06 00:39      
         using micro      Suresh R      02/02/06 00:25      
            Microcontroller      Andy Neil      02/02/06 01:35      
               Pressure      Steve M. Taylor      02/02/06 03:51      
            What must your circuit can do?      Kai Klaas      02/02/06 07:17      
               0.1 sec      Steve M. Taylor      02/02/06 10:34      
                  but not with a potentiometer      Erik Malund      02/02/06 10:38      
                     Vernier      Steve M. Taylor      02/02/06 13:02      
                        and calibrate it how?      Erik Malund      02/02/06 13:14      
               Precision        Andy Neil      02/02/06 15:13      
                  Sure!      Kai Klaas      02/02/06 16:01      
                     Price      Andy Neil      02/02/06 17:06      
                        Less than 1      Kai Klaas      02/02/06 20:02      
                           levels of precision      Suresh R      02/03/06 05:01      
                              Please have a look into datasheet!      Kai Klaas      02/03/06 05:57      
                                 somewhere here there is a link      Erik Malund      02/03/06 06:51      
                                    Details?      Kai Klaas      02/03/06 07:17      
                                       I recall that in an earlier thread      Erik Malund      02/03/06 07:20      
                              Ooops.      Steve M. Taylor      02/03/06 09:49      
                              Blown Discharge PIN      Abhishek Singh      02/04/06 19:15      
                                 You can also let the smoke out of the      Terry Lingle      02/04/06 22:37      
                                    limits      Steve M. Taylor      02/05/06 06:13      
                                       dissapation      Terry Lingle      02/05/06 09:45      
                                          There must be a point.      Steve M. Taylor      02/05/06 10:31      
                                             Fusing the bonding wires      Terry Lingle      02/05/06 13:59      
                                                History making      Steve M. Taylor      02/05/06 14:47      
                                                Current limiting      Kai Klaas      02/07/06 06:42      
                                 I do go through      Suresh R      02/07/06 01:50      
            schematic and code      Kai Klaas      02/05/06 19:47      
               codes      Suresh R      02/07/06 00:32      
                  Instruction Description      Andy Neil      02/07/06 04:28      
                     not quite      Erik Malund      02/07/06 06:09      
                        Pedantic      Andy Neil      02/07/06 07:12      
                           is that not the pot calling the kettle b      Erik Malund      02/07/06 07:17      
                              Of course not!      Andy Neil      02/07/06 07:31      
                  Answers      Kai Klaas      02/07/06 07:55      
                     Re: codes and shcematic      Suresh R      02/10/06 03:55      
                        Recommendations      Kai Klaas      02/10/06 07:05      
                           Decimal switches - how to start C      Erik Malund      02/10/06 08:09      
      LM555 pin 2 wired wrong.      Charles Bannister      02/01/06 04:45      
         ... and the LED?      Andy Neil      02/01/06 05:31      
            i'm sure thts not the circuit      Abhishek Singh      02/01/06 06:38      
            Astable??      Kai Klaas      02/01/06 11:46      
               I wondered who'd spot that first...      Andy Neil      02/01/06 12:47      
   Damaged?      Kai Klaas      02/01/06 11:51      
      And Andy's correction      Steve M. Taylor      02/01/06 12:03      
         Absolutely!      Kai Klaas      02/01/06 12:24      
   one shot in the foot      Erik Malund      02/01/06 12:31      
      Need not to work unreliably      Kai Klaas      02/02/06 07:10      

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