Summary of Robert Brown Arduino dew controller build

Overall I’m very happy with this project. It seems to work very well and is a huge improvement on not having dew straps. Generally it’s a pretty straightforward build with nothing really that much more taxing than making sure LED polarities are correct and so on.

Over the last couple of days I’ve built a third controller that I’m in the process of testing. My next step is to build some focuser controllers, but I do also intend to build one more dew controller to go with my travel kit. Depending on my experience with the focuser controllers I might actually make single box containing focuser controllers, dew controller and RPi to reduce the number of things I need to carry around, but without an LCD display and probably the dew strap LEDs. It will probably be wise to keep the fan as my travel kit often goes with me on summer holidays and even in France it can be as much as 30C overnight.

I think I will probably also swap my first controller from the 6P4C connectors for the temperature sensors to GX12 plugs, but there’s no real hurry for that.

Another thing there’s no urgency over is the possibility of an improved design for the temperature sensors themselves. The ones I have (which I believe are the ones recommended) have the sensor inside a metal barrel about 60mm long and 8mm in diameter, which isn’t always the most convenient shape to use on a small OTA. I’ve been wondering if I could use the DS18B20 case style that’s used for the board temperature sensor and perhaps epoxy it to a small piece of stainless steel sheet. With the wiring I think the entire sensor end need only be about 10mm by 30mm which might be more practical for small OTAs.

Actually, that’s probably something else worth mentioning… Attaching the temperature sensors. I’ve no idea what the best way to do it is, so what I have at the moment is a strip of thin camping mat long enough to go right around the OTA. The sensor goes underneath that, and it’s all held in place with a velcro strap, just behind the dew heater itself.

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