It has been a while since I made any progress on a project, so I thought that I would put something down here as a way of summarising to myself where things are, what is left to do and so on, as a form of to-do list.
Cloud Detection#
This is the ongoing project to measure cloud cover, as discussed in this series of articles. So, what’s left to do?
Packaging it up#
As discussed I am still looking to package the system up using a combination of external mains junction box, various bits of plastic plumbing pipe and drainage pipe, expoxy resin and silicone sealant.
Reflecting surface#
The IR sensor must be kept out of the way of inclement weather. This means housing it in such a way so that it takes its measurements indirectly via a reflecting surface, such as a home made polished aluminium mirror. Regarding how to deal with dew, the mirror must come equipped with a temperature sensor and heating element bonded to the rear non-reflecting surface.
Things to do#
Research into the following:
- Building a heating element (probably Nichrome wire)
- Heater control and feedback (see below)
- Mirror thermal properties, i.e. mass and dimensions
Dealing with Dew#
The reflecting surface will at least partially be exposed to the sky thus necessitating a method or two of keeping dew at bay. I am currently thinking of constantly sampling the mirror temperature and using that to feed back to a light duty heating system, comprising a nichrome wire heating element, to keep the mirror a couple of degrees above dew point. Additionally I am considering using a small fan to keep air moving in the space between the IR sensor and the mirror.
Things to do#
Build a prototype circuit with an Arduino as a controller containing the following:
- A DHT22 humidity sensor and required code to calculate local dew point temperature.
- A DS18B20 temperature sensor for measuring the reflector surface temperature.
- A relay or transistor to control the reflector heating element and fan.
- A bicolour LED to indicate heating on / off.
- Write a brief blog entry about it in the projects section.
Soil Temperature Monitoring#
This system has spent well over a year working “in production”. I’ve only had to address some reliability problems with the networking, as discussed here, by giving the Arduino a heartbeat and here regarding the W5100 ethernet shield.
Camera Bird Box#
This is a project I have thought about doing for years. Probably these days it may be cheaper to go an buy an internet-ready bird nesting box with a HD quality camera inside, but where is the fun in that? I have spent a few nights putting a few hours into the cunstruction of a bird box with space to fit a modified cheap USB web cam from my local Maplin store. I’ve retrofitted some bright IR LEDs to give a little light so that the chicks can be seen (and hopefully only gently warmed in the IR glow!). I have all the materials required to complete this project - the only other thing I need to think about is to write an entry or two on here at some point.
UV Light Box#
A friend at work and I have shared many an hour discussing Arduino projects, and after many circuits built using veroboard we decided to have a look at prototyping some custom circuit boards. Not being up for the old fashioned approach of drawing out circuits on board by hand, we decided to have a go at laser printing them instead. There is no need go through the whole process of how one can home-make PCBs, so here is a handy guide. It just suffices to say that we wanted to have a go at a UV exposure method for masking the circuit board prior to etching.
A little bit of research will tell you that these UV light boxes are quite expensive, so why not make a DIY version instead?
Laser Visibility Detector#
This is based on another thought that kept me awake one night (yes, I must learn to think about more interesting things!). Listening to the shipping forecast on Radio 4 I always wondered how the visibility was measured. Traditionally, of course, this was done simply with a manual observation of objects at known distances. These days measurements are taken using instruments using xenon beams and sensors separated by a short distance.
I got to thinking about whether I could do something similar using a cheap laser diode and a detector to measure the loss of light by scattering over a small distance in the garden.
At this stage the whole thing is a proof of concept and another excuse to spend a few hours in the workshop playing with electronics. I have a few ideas about how to build the thing and have started prototyping some small circuits. Again, it is probably time to start writing an article on here about it.