From: localhost@127.0.0.1   
      
   I need to control two 120VAC/5A heating elements off a 240VAC supply.   
   Two elements will be plugged into one control box and ideally one   
   "temperature control" is to be fitted to the box. The elements can be   
   unplugged so that only one element might be operated at any one time. Cost   
   as always is a factor (as is with most customers!).   
      
   The customer suggested a cooker type infinitely variable simerstat, as this   
   would be good enough for the type of temp control they require.   
   The only simerstats available locally are 240V and the manufacturer advises   
   that they will not function properly on120V. Then there would be the need   
   for interface relay/contactor to switch the element etc. etc....   
      
   My first thought were to use a 240/120 transformer with a thyristor circuit   
   on the 120V output.   
      
   My second thought was to use a thyristor without a transformer, restricting   
   the the thyristor output to a max of 120V via the thyristor control circuit.   
   The problem with this is that a short-circuited thyristor would apply 240V   
   to the elements causing problems. A fuse in circuit yes, however this   
   equipment is to be used in a rough industrial environment, meaning that the   
   operators WILL replace expired fuses with fencing wire!   
      
   Any ideas, past experiences, circuit suggestions using triacs, back-to-back   
   SCR's or whatever would be appreciated.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)