Posts Tagged ‘arduino’

Cheating mobile step counters

Monday, May 4th, 2015


Got involved in an inter-agency stepping competition using an app-based pedometer. It seemed kinda accurate but inevitably, my curiosity drifted towards trying to figure out how to automatically gain steps while watching TV.

Cue my trusty Arduino, a small RC car servo, some blu tac and some precisely tweaked variables. Took a while to find the optimum ‘swing, pause, swing back’ timings. Too quick and it didn’t register the pauses either end. Too slow and it didn’t think it was a complete step. Eventually arrived at the Goldilocks setting. Just right.

Here’s the result. Works with a FitBit too btw.

Persistence of vision test with LEDs

Thursday, March 5th, 2015


back in the 1980’s, there was a catalogue called “Innovations“. It was full of all sorts of gif gadgets and nic-nacs. I was always fascinated by a clock that looked like a metronome. As the arm moved backwards and forwards, it seemed to spear the time in light in thin are. This was my first introduction to persistence of vision (aka POV). Essentially you eyes not keeping up with reality and leaving slug trails of light on your retinas.

I had a thought… would it also work if the clock arm stayed still and your head moved from side to side? Could I install a single column of flashing LED lights and create POV images in your vision?

The image above is my first experiment. 9 LEDs in a strip, merrily flashing away and me moving a camera with a relatively slow shutter speed from left to right. It does actually replicate what I saw with my actual, organic eyes but saves on the pounding headache I induced will testing it. Turns out heads aren’t supposed to change direction that quickly.

Here are two other images that show it goofing up slightly as you can get a better idea of what’s going on.

800_IMG_8886 800_IMG_9005

The slight flaw in my plan was that those clocks (and the funky LED wheels) take advantage of a sync point. I.e. each tick of a clock resets the flashing so that the lights smear in a repeated, exact position each time. With a shaking head, there is no syncing up between the lights and the head. Each time the head moves, the lights may be flashing a different part of the message, so it’s hit and miss as to whether you see the full pattern or some crossover bewteen the start and the end.

Either way, it works. Just go to build one 200 feet tall…


Cookie Clicker – iPhone ‘cheat’

Sunday, November 24th, 2013

I like my cheats a bit old-skool so came up with this way of getting up to 50 clicks per second using a small solenoid to move your finger for you! Lazy? Yes. Cunning? Yes. Practical? No, not really. But hey, it’s only clicking a cookie.

Here’s the science… I used a small solenoid controlled via an Arduino board connected to my computer to ‘tap’ my finger. Took about 10 mins to put together with the help of this great tutorial on Instructables, and even uses the built in basic ‘Blink” Arduino demo code. Easy!

This example is a bit clunky but when you hit the sweet spot, it’s doing 50 clicks per second. More if you tweak the code. In fact, the app hangs it clicks so fast!


UPDATE: I original solenoid in this video was quite weak and didn’t have a return spring (I had to improvise one), so I ordered a new one of Ebay described as “DC 5V 1.1A Pull 5mm Stroke 50GF Force Open Frame Solenoid Electromagnet“. Try searching for that if you want one too. Cost about £3.60 and looks like this…

Incidentally, I did try to make a ‘false finger’ using an old Nerf dart covered in that anti-static bag stuff, but in the end, a real finger was much more reliable. And yes, you could just edit the plist, but where’s the fun in that!

Right, back to doing important things…