Expo conv. heater (tomg et al.)

[terry michaels]

Hi All

The recent thread on heated expo converters correctly discussed some of the
drawback:  increased leakage current, permanent change in tranny
characteristics if heated too high, mechanical stress, possible decreased
reliability.  Ok, how about an alternative: cool it instead.  You can get
Peltier junction coolers from many sources of surplus components pretty
cheap, just monitor Vbe and drive the Peltier in a closed loop (don't
forget to invert the gain stage, so you still have negative feedback).  The
reduced temperature will greatly reduce transistor leakage current,
reliability shouldn't be affected, and who cares if it gets too cold
(unless ice forms).  One drawback, the Peltier sucks a lot of current.
 Terry Michaels