Eyepiece box heater
Posted 05 January 2013 - 04:58 PM
I have a hundred feet of roof heating cable plus hundreds of 1/2watt 330ohm resistors to play with.
How big of a pad would I need to make or should I snake something around base of eyepieces?
I also have a old heater strip from a 8in SCT I could glue to the inside if that would work.
How much warmth is enough in a box ? Any ideas or thoughts
Will be used with a DewBuster controller.
Posted 05 January 2013 - 07:56 PM
Posted 05 January 2013 - 09:00 PM
Posted 05 January 2013 - 09:07 PM
A wooden box has some natural insulation so may not need the blanket.
Depending on the size of the box, it's construction, and how cold it is outside, I would think you may want 2watts up to as much as 10 watts or more. Since you plan on using the dew buster, why not build for 10 watts and set the buster as needed to keep things warm. In a closed box that is insulated, 10 watts is a lot of heat.
Posted 06 January 2013 - 09:48 AM
Posted 06 January 2013 - 12:50 PM
so 12v. Not being in direct contact with the eyepieces I would be relying on radiant heat. I can build a 6"x4"pad underneath the eyepieces with all heat going up (approximately 4 or 5 watts max ) The dew strip I have would wrap around the ID of the box and has a rating of 25watts but would heat from the sides of the box. I'm more worried about how much is enough or am I over thinking?
Posted 06 January 2013 - 01:59 PM
Posted 07 January 2013 - 12:03 AM
Posted 09 January 2013 - 04:16 PM
Posted 09 January 2013 - 09:22 PM
Posted 09 January 2013 - 09:48 PM
And, man, we get some DEW in Central Kentucky! (Probably like much of the central part of the U.S.)
Frankfort KY USA
Posted 11 January 2013 - 07:12 PM
12in long rated 85w 120v. I don't know if it can work with 12v without overloading/heating the wiring. Time to play!!
Posted 13 January 2013 - 12:56 PM
Posted 13 January 2013 - 01:14 PM
Posted 13 January 2013 - 05:39 PM
Sorry Mike, but your 85 Watt element (at 120V) will only operate at about 1 watt when driven at 12V. Again and again Astro Based people's electrical advice is just astonishing!
I would use oversize 10 watt ceramic resisters instead and mix in some LEDs to give some free light.
Should you want to solder Nichrome wire use hard silver solder and an alum based flux. Must use a small propane torch for this higher melt solder. Only buy from a welding supply outlet. Hardware stores ONLY sell junk hard solder. Gene
Posted 14 January 2013 - 02:32 AM