Thanks, Chris, for sharing all these precious information
I have checked other similar dew heaters as well, but yours is the simplest with no need for any custom PCB, few ready to buy components, easy to build, and still with great functionalities. I already ordered some components that I was missing in my stash - like expansion boards, Mosfets, AM2320 etc.
For dew heater, I mainly use the element from inside the Pipe Heating Cables available here in Canada. I cut the desired length and connect it with either an old USB cable (for 5v), or some 18-20 AWG wires for 12v application. I have been successfully using them since 3-4 years now with ZERO issues. They are all covered by a Velcro tape (on one side) and a thin cotton tape over the Velcro, while the element is lightly covered by the same thin cotton tape.
This time, I want to go for Planet photography using my 8" and 12" Newtonians, and I want to have a smart control on dew heaters so as not to overheat the primary mirror. That's where I came across your smart dew heater page.
I will keep you posted with the progress. I am attaching some pics of my dew heaters.
https://photos.app.goo.gl/mgBL2ZYQBx3RDiWc7