Astronomy: DIY Dew Heater

Posted on by AstroPilotDad

Whether you are a visual astronomer or astro-photographer, one challenge that every one of us faces is dew. Without proper dew management techniques, we run the risk of ruining a perfectly clear night. As you know by now, I live in the Pacific NorthWest and I would hate to lose a perfect night especially when we get so few clear nights to begin with. Right now, its been almost 2 months that I had an opportunity to take my telescope out so dew should not be a reason to pack-up the night. Luckily, there are several dew heaters available in the market to choose from. However, they range anywhere from $50 to $200 with controller costing another $100-$150 bucks. Since Astronomy is an already expensive hobby, I thought I’d use some of my shoddy DIY skills to build a dew heater for myself and document the process along the way. In all, the whole set up doesn’t cost more than $25-$30 but it gets you enough raw material to make several dew heaters of various sizes to fit your equipment including telescopes, guide scopes, eye pieces and camera lenses. The most important thing for building a dew heater is the power output. From looking up online, I found that 0.3 W/cm is considered good output for a dew heater and based on my field test, that’s works. The video below documents my process for building a dew heater. This is my first attempt at vlogging so please bear with me for any noob mistakes and for the pace of my narrative. It is unscripted 🙂

Here is a list of all the items (along with the links to the ones I used) needed to build your own dew heater:

  1. Heating Element (Nichrome Wire)
  2. Heat Shrink Wrap
  3. Dimmer Switch
  4. Wire
  5. 2.5mm jack
  6. Power adapter
  7. RCA Jack
  8. Velcro (optional)

These are the items that go into the dew heater itself. There are other tools (for example: a soldering gun) required to complete the project which are are apparent in the video so I will not be listing them here.

As for the calculation on what gauge Nichrome wire to get for the length of the dew heater. Here it is:

I searched the internet for the wire whose resistivity matches closes to what I needed (16 ohm/ft) and found that 34G fits the bill. Hope this helps!

I was hoping to have a fancy calculator where you input the details and it spits out the resistance that you need but that is not available in the premium subscription I have for my website :).