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???
05/05/10 05:06
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#175692 - 25V is not bad
Responding to: ???'s previous message
Hi ,Arun,
I did not understand - what is Your final product.

If its some UPS supervisor - higher level of safety (of device functioning) is desired. I do not claim that opto is best decision - You will take decision.
For such device i think transformer is best , but its really costly and big.

If device is dimmer - first of all - how many wires will go to them - 2 or 3 ? If it's not permanently powered by mains (2 wires only instead 3 wires) - 1..2,5 mA is limit for consumption - and 89s52 is far away from this point.If You have 3 wires 89s52 can be used but powering is still problem - 10...20mA results in big head dissipation, unless You use SMPS or trafo.
But if You use SMPS or trafo, then ZCD via resistor is non-elegant.
And price of optocoupler is not so important , even in 100k series - quality of product is more important.

My friend produces 2-wire dimmer with PIC12f509 , RC powering, triac and infrared receiver, mounted instead wall switch(i'm involved in firmware here). For 8k devices sold, i didn't know any problems with R,C,micro or IR , caused by high voltage spices . Some devices come back with dead triac - but what exactly is reason , hi dont know. (End of life in incandescent lamps is really high power event :-) .

As about 25V with 2 optocouplers..... If You use power enough micro with 2..3 timers - You can measure period , length of ON and OFF states and calculate where exactly is zero crossing. And You can do this permanently.

regards



List of 86 messages in thread
TopicAuthorDate
External Interrupt on both Falling edge & rising edge            01/01/70 00:00      
   ABORT!, ABORT!, ABORT!            01/01/70 00:00      
      Better circuits exists            01/01/70 00:00      
      one more            01/01/70 00:00      
   DANGER!! Don't Try This At Home!            01/01/70 00:00      
      Its not just Atmel            01/01/70 00:00      
   interrupts on both edges            01/01/70 00:00      
      Thank you All            01/01/70 00:00      
         Read about external Gate for Timer            01/01/70 00:00      
            gate for timer            01/01/70 00:00      
               Jan, will you Shhhhh!!!            01/01/70 00:00      
               Great Idea !            01/01/70 00:00      
                  But i've used up INT0 and INT1 pins            01/01/70 00:00      
                     int0 is gate for timer0            01/01/70 00:00      
                     T1(T0) pin is not use here            01/01/70 00:00      
                        so only one Ext.int pin will do            01/01/70 00:00      
                           i think so            01/01/70 00:00      
                              I haven't tried it yet            01/01/70 00:00      
                                 is a Zener that costly?            01/01/70 00:00      
                                 so try something safely            01/01/70 00:00      
                                    That the most exhaustive reply i got so far !            01/01/70 00:00      
                                       You are wellcome            01/01/70 00:00      
                                          Here's what i have done            01/01/70 00:00      
                                             simulation is partial            01/01/70 00:00      
                                                I'll try writing a sample code            01/01/70 00:00      
                                                   Dimmer            01/01/70 00:00      
                                                      its a dimmer for commercial sale            01/01/70 00:00      
                                                         Dimmer            01/01/70 00:00      
   Its in my Profile            01/01/70 00:00      
      is 8051/2 I/O similar to Zilog Z8            01/01/70 00:00      
         Cease and Desist            01/01/70 00:00      
         It's DANGEROUS - It's not about the IOs!!            01/01/70 00:00      
         Either you are NOT listening...or you don't want to listen            01/01/70 00:00      
            It's worse than that!            01/01/70 00:00      
               Its like openning Pandora's box            01/01/70 00:00      
                  chip A != chip B != chip C            01/01/70 00:00      
                  Consider these points...            01/01/70 00:00      
                     not a newbie to electronics            01/01/70 00:00      
                        What results do you really get from an experiment?            01/01/70 00:00      
                        Reply to Arun Kumar V            01/01/70 00:00      
                  what if the result is death?            01/01/70 00:00      
                     very positive opinion            01/01/70 00:00      
                     Thanks for the pointer            01/01/70 00:00      
   A generic approach to dual edge detection            01/01/70 00:00      
      Here is the method I have been using...            01/01/70 00:00      
      Oh Noes!!!!!!            01/01/70 00:00      
      4 -> 10 nsec Pulse Does Not Work for MCU            01/01/70 00:00      
         No additional logic gates            01/01/70 00:00      
         Modifying design            01/01/70 00:00      
            Yeah But...            01/01/70 00:00      
               If you say so            01/01/70 00:00      
                  Poppycock            01/01/70 00:00      
   Why you should not do this...            01/01/70 00:00      
      Galvanic isolation            01/01/70 00:00      
         Can't we use single AC optocoupler            01/01/70 00:00      
            not 1,8V            01/01/70 00:00      
            can be wrong circuit below            01/01/70 00:00      
               Critical again...            01/01/70 00:00      
                  varistor?            01/01/70 00:00      
                     Yes, but...            01/01/70 00:00      
            You can do a lot of things...            01/01/70 00:00      
               25V is too coarse            01/01/70 00:00      
                  use tha appnote I gave you the link to            01/01/70 00:00      
                  25V is not bad            01/01/70 00:00      
                     You still don't know what my product is?            01/01/70 00:00      
                        sorry            01/01/70 00:00      
                           Its O.K - this thread has crossed 65 replies            01/01/70 00:00      
                              npn            01/01/70 00:00      
                        no, I do not know what your product is            01/01/70 00:00      
                           Answers            01/01/70 00:00      
                              OK, then            01/01/70 00:00      
                                 No headphones            01/01/70 00:00      
                  Then take a better opto!            01/01/70 00:00      
                     he wants to build a Yogo, not a Mercedes            01/01/70 00:00      
                        which makes the lamp flicker when the fridge turns-off            01/01/70 00:00      
                           it (probably) does that anyhow            01/01/70 00:00      
                              No body wants to buy a Mercedez            01/01/70 00:00      
                                 What do you expect??            01/01/70 00:00      
                                    What is there to be ashamed of ?            01/01/70 00:00      
                                       Thread began with ....            01/01/70 00:00      
                                          Dead Horse is Alive and Kicking            01/01/70 00:00      
                                             obviously a comparator is a better solution            01/01/70 00:00      
                                                Oh My God...you having sleepless nights???            01/01/70 00:00      
                                             Then share it with us...            01/01/70 00:00      
                                             to Arun PLEASE get ...            01/01/70 00:00      
                                 what did you expect            01/01/70 00:00      

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