Monthly Archives: July 2014

“light” relief

light-lessonIt’s summer, so Jean is engaged in a little “light” relief — a session for Christ Church Morningside’s Holiday Club Children about how we see colour.    We’re going to play a game where they’re light of different wavelengths, an eye, a brain – and of course, a scientist, since we need at least one of those to understand what’s going on.    First the light will arrive at the eye one colour at a time and we’ll learn what the cones do.  After that, we have to solve the puzzle of what happens when more than one comes together.  Then we’ll introduce how normal white light is made of all the colours, and finally get to translucency, reflection, and what happens with coloured materials.  Jean’s hoping that there will be time at the end to try what we’ve learned.  Even resident scientists like to paint!

three-colour-switchesOf course, this being Heathack, the entire session is partly born of curiosity, and partly just an excuse to show them a little electronics.  They’ll have to cooperate to find out what red and green makes using a simple three-switch circuit controlling the different colours. If they’re curious enough, and Jean gets it working in time, she may even show them the “eye” she’s building.  It’s a colour sensing circuit that uses an RGB LED to bounce red, green, and blue light off an object one colour at a time, so that a light dependent resistor can judge the amount of each it receives back.  Simple in theory, but as usual when building measurement devices, good calibration takes most of the effort.


The last package has arrived, so we’re now officially well-equipped!  It’s a USB rechargeable battery that will run a Raspberry Pi – together with a 80p microcontroller just powerful enough to wake up every so often and decided whether it’s time to boot the Pi yet, it’s our solution to some of the trickier church spaces with no electric sockets.  In the interests of transparency, and for those who like all the gory details, the full list of electronics-oriented equipment the University of Edinburgh’s School of Informatics has placed at our disposal is here.  We think it makes an excellent start.

Ready to goThere are plenty of fun bits and pieces to let us do some serious design work, but the largest part of the equipment is for building wireless sensor networks in our two host churches, showing that even rank amateurs like ourselves can help wtith whether the churches are getting the most out of the energy they put into their buildings.  The most basic sensor locations will report their air temperature and relative humidity via radio to a very cheap computer (Raspberry Pi) that can process the data and send it out over the internet for web display. This, some information about the building, and meter readings, for the moment by time lapse photography, is enough to build a reasonable building model that can answer the what if’s – what if we insulated the roof, heated the building a little all the time, and so on.  This part of the project just takes replicating what many hackers before us have done in houses using open source software they’ve graciously provided, but even that requires us to teach other soldering, web development, communication protocols, the psychology of thermal comfort, … everyone has something to bring, even if it’s only knowing what the building is like for them.  Once we have these basics at our command, we’ll be ready to start lending out networks to people who want to understand other buildings and help them build more.  The price of entry is something like £45 per building plus £35 per sensor location – not nothing, but affordable if we all work together.

upcoming events

We have three upcoming events soon – all stalls that will be our first chance to show the people passing what HeatHack intends to do.  They are:

It’s very unfortunate that no one is available to attend the Wardie Fair, but we do want to at least send a poster.  They’re one of the churches that’s been monitored as part of Science of Church which means we can show them their own data.

We’re working on a few things to show.  The most important is temperature and RH sensors communicating readouts to a Pi base station, with display of the current readouts on a laptop.  Preferably the display will be in a web browser so it isn’t scary, not just in the serial monitor in the Arduino IDE!  The second is just one of our homemade camera installations with a video looping through timelapse gas meter and boiler light pictures – not gripping images, obviously, but they are useful.   We’ll also have some graphs of synchronized read-outs for a church to show why this kind of data is useful, and maybe also some preliminary design sketches for some of the more advanced setups we want to build, like hot wire anemometry and readings at ceiling level where there’s no access.

If you’re interested, we haven’t launched properly yet, but we are meeting up at the Methodist Church on second and fourth Tuesday evenings – early adopters welcome, please leave a comment to get in touch.