From: baron.nospam@linuxmainiac.nospam.net   
      
   John Fields wrote:   
      
   > On Sat, 20 Oct 2007 00:15:56 GMT, "Farticus"    
   > wrote:   
   >   
   >>   
   >>"John Fields"  wrote in message   
   >>news:519ih3dgdj0lg36f01a48e6887ehk8a988@4ax.com...   
   >   
   >>> From the point of view of cost, I like the idea of a single   
   >>> phase-controlled TRIAC driving both heaters in parallel since the   
   >>> pair of heaters, in parallel, will only need 10A from the mains and,   
   >>> with proper timing, the loads will never see more than 120V.   
   >>>   
   >>> When one is unplugged, of course, the TRIAC need only pass 5A.   
   >>> Even better.   
   >>>   
   >>> But what's a simerstat?  Is it a device with feedback which will   
   >>> maintain a temperature once set, or is it like an open-loop lamp   
   >>> dimmer?   
   >>>   
   >>>   
   >>> --   
   >>> JF   
   >>A simerstat is the term given by electrical wholesalers for a control   
   >>typically used to control a cooker plate. It is open loop.   
   >>The simmerstat has a bi-metal strip built into it that does the   
   >>"control". The simerstat usually incorporates a 1amp(or thereabouts)   
   >>rated contact that is used to control the cooker plate (element).   
   >>F.   
   >   
   > ---   
   > I'm confused.   
   >   
   > If the simerstat is used to control temperature and the bimetallic   
   > switch is used to switch the element on and off in order to maintain   
   > that temperature, then that's closed loop.   
   >   
   > An example of 'open loop' would be a lamp dimmer where there is no   
   > feedback used to control the brightness of a lamp.  Or, for another   
   > example, a VARIAC.   
      
   Hi John,   
      
   The simmerstat is only open loop in the sense you describe.  There is no   
   sensing of the actual hotplate temperature.  The current through the   
   hotplate passes through a secondary heater wound around a bimetallic   
   strip.  This simply makes/breaks the circuit.  A cam controls the   
   distance the bimetallic moves.   
      
   --   
   Best Regards:   
                        Baron.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)