-=> Mike Ross said to Greg Mayman
 -=> about "{at}%^{at}#$%^ VEROBOARD" on 03-31-04  08:41.....

 MR> I think you have a misplaced trust in electro-mechanical devices.
 MR> Mechanical relays will eventually wear out and stick or a piece of
 MR> dust or other contamination blocks the contacts. OTOH a solid state
 MR> switch does not wear out nor get dirty. What else is there to say!?

1. Electro-mechanical switching has been in use for over 100
   years, during which time the techniques of designing,
   building, using and checking them have been continually
   improved.

2. Electromechanical switching systems are open for visual
   inspection, and virtually all defects can be observed and
   corrected before they affect the electrical switching. For
   this reason, they are always given a regular maintenance
   regime.

3. Contacts on relays in high reliability systems are always
   duplicated, and in addition they are designed to have a
   sliding, selfcleaning action which tends to remove dirt, oxide
   etc. When one of the multiple contacts becomes so contaminated
   that it fails to work, the others will carry the load until a
   visual inspection of the contact shows up the fault and the
   contact can be manually cleaned.

4. Solidstate switches either work or they don't. There is no
   simple method of detecting whether one is about to fail, until
   it actually does fail.

What else is there to say?

   ,-./\
  /     \ From Greg Mayman, in beautiful Adelaide, South Australia
  \_,-*_/    "Queen City of The South"    34:55 S  138:36 E
       v

... Of all the people I have met, you are certainly one
___ Blue Wave/386 v2.30

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