How would you like to own the most talked-about pushbike in the school/street/suburb... galaxy? Build this POV display and you’ll be well on the way.

You really have to see it to believe it – and we’ve even made it easy for you. As well as the images printed here, there are several more you can view online at www.ianpaterson.org/projects

OK, you’ve now seen them and you’d have to agree that they look pretty spectacular, right? You want to do the same for your pushie? Just make sure you keep it chained up because everyone will want it . . .

Persistence of Vision

You probably don’t realise it but you use POV every day – when you watch TV. Movies also take advantage of this phenomenon.

The TV and movie picture is not continuous vision – rather, (in the case of TV) 25 individual pictures are displayed every second. But your eyes and brain cannot follow the 25 individual frames of picture per second – instead, they "fill in the gaps" and you "see" full motion, non-jerky video.

Talk about WOW! factor: this three-high static display uses different coloured LEDs in each wheel to reveal three different patterns. The "rider" powers the first wheel and the second and third wheels are driven by friction between the tyres.

If you slowed those frames down to, say, ten per second, you would be able to see the period between each frame and it would become jerky – just like the old-time movies where the hero moves like a Thunderbirds puppet.

Let’s take this one step further. Say you had a moving light – we’ll make it a LED because they can be turned on and off very quickly - which you flashed on, very briefly, once per second. You’d see this as flashes of light moving along a path. If you changed that to, say, ten flashes per second, you’d probably still see flashes but very much closer together. Make that fifty flashes per second and the flashes would all meld into one another. You’d see it as a continuous line of light – even though your brain knows full well that it is flashes you are viewing.

That’s persistence of vision and is the basic theory behind this project. Rows of LEDs are made to flash too quickly for your brain to process, so they appear to be permanently on. The rows of LEDs are mounted on PC boards fixed to a bicycle wheel, so they follow a circular path as the wheel rotates.

By using some clever circuitry to switch the LEDs on and off at particular moments, a pattern or picture can be created – in fact, the display is almost unlimited. It can be everything from geometric shapes to text,cartoon characters and even very high contrast pictures (see examples below).