Re: [ATM] Electronics help needed - temperature control

[Ken Hunter <atm_ken_hunter@yahoo.com>]

Ahem...
   
  Saved $20.00 on a mirror blank, bought a plate glass one that's 3/4 inch thick.
  Also saved some weight, maybe a couple of pounds.  I can now lift the scope to
  put it in the car but ...
   
  I will now need to spend $2500.00 on Peltiers, heatsinks, fans,  low voltage-high 
  current regulated power supplies and controllers, a generator and of course a small
  trailer to haul it all in.
   
  Anybody make any sense out of this?
   
  Ken Hunter
   
  

Don Clement <clement.focuser@verizon.net> wrote:
  
> So Don, how about mods to run a fan off of the differential circuit?

The purpose of my differential circuit was to automatically keep optics a
small amount above ambient with parsimony. For automatic dew prevention
this circuit achieve that purpose. I don't know what the application using
fans to set the temperature of a mirror is. If the purpose is to keep the
mirror at a preset temperature or to eliminate temperature variation across
the mirror, I would use something much more complex, such as an array of
linear bandgap temperature sensors and an array of Peltier devices with a
proportional controller. There would be added complexity of eliminating the
heat from the hot side of the Peltier devices. I only suggested a simple
modification to using my differential circuit so it would work for a preset
level. YMMV.



Don Clement

Running Springs, California

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