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???
11/16/07 19:07
Modified:
  11/16/07 19:08
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 		 #147091 - Taking notes...
Responding to: ???'s previous message
Russell Bull said:

1/ Clearance between the relay contacts and everything else. I don't know what voltages are being switched, but it wouldn't want to be 230VAC.


Relays switch low voltage/low current.

Russell Bull said:

2/ Input protection for the 7805. I can see a reverse polarity diode and a capacitor but that's all. I'd slap a transzorb and a polyswitch on the input to take care of transients.


Well, these are things that I certainly should consider in next revision.

Russell Bull said:

Depending on what the relays are switching, some snubbing across the load or the contacts will help enormously.


Relays aren't allowed to switch big currents so snubber may not be needed here.

Russell Bull said:

The closeness of the DC input to the relay contact wiring is a bit of a worry, make sure this is separated. Make sure the input wiring is separated from the switched loads to minimise pickup.


That's right. I need to move the DC input to somewhere farther.

Russell Bull said:

The rS485 doesn't look like it has any protection. My usual protection is sa5.0 transzorbs and 100mA polyswitches in series along with 10R resistors on the + and - signals.


The rs485 line has transorbs but no polyswitchs.

Thanks for all of your advices. I'm making a list of things to be done and this thread has been quite helpful for me.










List of 88 messages in thread
TopicAuthorDate
Atmel 89 Series and EMI            01/01/70 00:00      
   FAQ            01/01/70 00:00      
      Thanks, but...            01/01/70 00:00      
         yes it is            01/01/70 00:00      
            EMI design consideration...            01/01/70 00:00      
               reset pulses?            01/01/70 00:00      
                  Finally a note to the OP            01/01/70 00:00      
                     well, sometimes...            01/01/70 00:00      
                     Fire Extinguisher            01/01/70 00:00      
                        extinguisher            01/01/70 00:00      
                  Latched-up CMOS!            01/01/70 00:00      
                     logic, and beyond            01/01/70 00:00      
                     not a cure            01/01/70 00:00      
   EMI Design            01/01/70 00:00      
      restated in one sentence            01/01/70 00:00      
         Don't jump to the conclusion...            01/01/70 00:00      
            then just say "outside the specs, no can do"            01/01/70 00:00      
      Thanks...            01/01/70 00:00      
   What PCB do you use?            01/01/70 00:00      
      Two Layer            01/01/70 00:00      
         No surprise, then!            01/01/70 00:00      
            Ground...            01/01/70 00:00      
               About naked firefighters...            01/01/70 00:00      
               Absolutely it is fair            01/01/70 00:00      
   Some advice            01/01/70 00:00      
      Yes, it's a bunch of measures...            01/01/70 00:00      
      Good points.            01/01/70 00:00      
         No, no, no,....            01/01/70 00:00      
            Remember            01/01/70 00:00      
         CMOS Latch up            01/01/70 00:00      
         NOPE            01/01/70 00:00      
            You think so...            01/01/70 00:00      
               No, it is not            01/01/70 00:00      
               A proper design would stand it!            01/01/70 00:00      
                  Proper design            01/01/70 00:00      
                     some of my definitions            01/01/70 00:00      
                     Me thinks...            01/01/70 00:00      
                        the real point            01/01/70 00:00      
            More advice            01/01/70 00:00      
               Does that mean, that...            01/01/70 00:00      
                  It's the designers responsibility            01/01/70 00:00      
                     No joke, but...            01/01/70 00:00      
                  EMI and 2 layers            01/01/70 00:00      
                     Yes, for tiny projects...            01/01/70 00:00      
               that something is possible/done succesfully            01/01/70 00:00      
   Show us your design...            01/01/70 00:00      
      Why? You want to make fun of it? :)            01/01/70 00:00      
         Or            01/01/70 00:00      
            You mean...            01/01/70 00:00      
               I do not know what Steve ment            01/01/70 00:00      
               Yes !            01/01/70 00:00      
         how about a schematic            01/01/70 00:00      
            Relays            01/01/70 00:00      
               Even then...            01/01/70 00:00      
         From what I can see            01/01/70 00:00      
            Mostly agree.            01/01/70 00:00      
               Layers, layouts...            01/01/70 00:00      
                  are you serious, or did you forget            01/01/70 00:00      
                     Sorry, I forgot...            01/01/70 00:00      
                     Is it good?            01/01/70 00:00      
                        Just a few points.            01/01/70 00:00      
                           I believe you!            01/01/70 00:00      
                        No harm, usually            01/01/70 00:00      
                  Separate Ground Planes            01/01/70 00:00      
                     Inter-plane coupling            01/01/70 00:00      
                     Cable entry point            01/01/70 00:00      
                        Thanks            01/01/70 00:00      
            what I do ..            01/01/70 00:00      
            half measures            01/01/70 00:00      
            Taking notes...            01/01/70 00:00      
               the downfall of many            01/01/70 00:00      
               Do some tests            01/01/70 00:00      
                  This can be deadly!            01/01/70 00:00      
                     Deadly?            01/01/70 00:00      
                        I'm sorry...            01/01/70 00:00      
         Farshad, I would never make fun of it!            01/01/70 00:00      
            Very Informative            01/01/70 00:00      
               Decoupling            01/01/70 00:00      
                  Thank you!            01/01/70 00:00      
               and not a word about 4 layers            01/01/70 00:00      
   paralelling            01/01/70 00:00      
      Why not using 10µF/10V/X5S ceramics?            01/01/70 00:00      
   more information?            01/01/70 00:00      
      Schematics would not be very "helpfil"            01/01/70 00:00      
      More information            01/01/70 00:00      
      The best stuff I have ever seen is...            01/01/70 00:00      
         Sorry, I forgot, that you must suscribe first...            01/01/70 00:00      
      John, I have seen....            01/01/70 00:00      

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