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Posted by on September 10, 2013 in Design, High Cross House |

Behind the scenes

Behind the scenes

The bits you don’t usually get to see.

When I’m making technology for installations, my primary goal is to make the technology as utterly transparent as I can. That means you don’t get to see the clunky and messy bits, only the sheer elegance and simplicity of the final design. Working.

As I’ve been developing the tea tray, I’ve been up to my eyeballs in wire and solder trying to perfect a system that’s not only transparent to the audience in High Cross House (many of whom are not used to interacting with art, and certainly not with the ‘language’ of interactive installations), but transparent to the staff, too. That means making something that is self-maintaining.

Aesthetically the piece has to fit with modernist clean lines as well as with the stark and beautiful design images that will be the rest of the exhibition. For that reason, we’ve moved from having a set of teacups along the middle of the dining table to having a tea tray on the sideboard in the dining room – simply because there was no way to avoid having a power cable trailing from the dining table in the original design. When wireless power is perfected and available (I tried to hack this, but without success), the piece would have worked in its original vision. But now everything is contained on a tray and there is one power cable that trails out of the back and down the back of the sideboard where it can’t be seen.

This isn’t the final teapot. I’ve managed to source an original modernist teapot on eBay which has a fabulous chrome cover – but you’ll have to come again to see that’ cos I don’t have it yet.


I’ve wanted all along to make the piece charge by itself so that volunteers and staff wouldn’t have to open up the teacups to turn them on and off; or worse still, to have to open everything up and then plug it in to charge. I contemplated putting a charging port into each cup but I didn’t want that visual intrusion (and I couldn’t put it on the bottom, for reasons you’ll see below). I puzzled over how to achieve this for weeks, playing with all kinds of wireless charging hacks at, each time failing to build one that worked. I hate it when these hobby sites have all these wonderful doodads that clearly have worked for the authors, but which I can NEVER get to work (well, that’s not quite true, but sometimes it feels like it). So instead I ordered a PowerMat system which is an off-the-shelf system designed for charging mobile phones and things, ‘without wires’. The charging take place through induction – through air using a magnetic field. This meant that it should be possible to build in a ‘receiver’ into a teacup and the ‘transmitter’ onto the tray and bob’s-your-uncle, the battery in the teacup would remain charged without further human intervention. By magic, as it were.

In reality, these PowerMat systems are designed with very low power so that they don’t cause all kinds of stray magnetic fields, and are designed so that the transmitter and receiver have to be very (very very) close together. That proved a problem. The only answer was to tear them all apart, rewire them, cut holes in the bottom of the tray to countersink the saucers, drill a large hole in the bottom of the teacup, and so on… all to bring the power transmitter as close as possible to the receiver.




The PowerMats are also designed so that they shut off once the battery is fully charged, which meant that they wouldn’t start themselves back up until someone had used a teacup and reset the cup onto its saucer. Couldn’t rely on that as a safe way forward so I had to build a custom bit of electronics to turn the powermats on and off periodically. That worked…


Eventually, after much gnashing of lots of body parts, it’s all working which means that I can now focus on editing content. Only 9 days to go (well, 8 now), so it’s all getting down to the wire.