Hello Guys Another pic of my Photography Skills

Yo !!


Ok, So coming on to the topic.


Homemade Smart Cycle Computer - Finalising Sensor's and INTERFACE

So, A Part of the project was to get a System of measuring the Speed, Distance travelled, Avg Speed, etc. In this blog I will review various mechanisms I tried and Which one worked the best


OK, Many of us are used to the Cycle computers the small little thing that tells us some important Information like The Speed, Distance and so on. . .

Or the One I was Eying For (As a prize from Element14)


I Tried getting my self one of those cheep ones and trying to Rip it apart. Unfortunately It seemed a lot more complex and I immediately realised that It will take a lot of effort to reverse engineer so I dropped and decided to explore how can we achieve the task.


Method - I Using a Limit Switch

The easiest method I came up with is using a Limit switch something like this



The Idea was to tie a small wooden piece to the spokes of the tire and the limit switch to the tyre frame so when ever the tyre rotates, it will press the switch and the same will be recorded in software

Unfortunately, I realised its the most stupid IDEA.

Why ??

Because, primarily The switch has limited click's and is prone to wearing as it contains mechanical parts.


Method - II Using Reed Sensor

Next, My GENIUS mind came up with a magnetic solution as these sensor were cheep in market (about 5-10 INR / couple of cents) and Internet blames these to be Magnetic switches.

So I grabbed few from market, made a small board for them as they are pretty delicate and started testing. Here's How they Work:


Well It does act as a Switch but with a very poor response, It took couple of milliSec for the switch to detect the magnet thus making the entire fast detection thing pretty much useless and another Fail exercise for the job.  


Method - III Using Hall effect Sensor (FINAL Method)

Well, we all love INTERNET and my Google Searching Skills payed off When I came across This beautiful device called as Hall effect Sensor , My eyes sparkled while going through the data sheet and my gut said; This is it.


and so I went miles to fetch one of these babies (Well eBay did all the travelling credit to them ) and I received the beautiful sensor. I immediately ripped the package grabbed a Yun, breadboard and couple of wires. After few minutes of a basic Arduino Sketch I was able to achieve what I wanted. A fast magnetic way to get the job done.


This is a Roucg Circuit Diagram


Click here for the Datasheet




Note : Few things in this video are recycled and are readily available for makers.

and you with couple of basic prying tools can get all required components easily from a Old DVD/ CD Writer. They use the Magnets near the lens assembly to move it and the Hall sensors beneath the spindle to sense the spin speed. 



Part List

Allegro A1104 Hall Sensor

10K Resistor

Bread Board

Couple of Single Strand Wire

Arduino development kit (Any Will Work I have tested using Yun)



In conclusion,

1.    This was more like an tutorial/ How to approach a problem given some constraints BLOG, So please do provide feedback if you guys think that it is a bit too kidish

2.    The prototype of Hall effect Sensor looks great and its time to get it to next stage. Lets design a PCB for the sensor Board and none of the CAD stuff, lets get a bit creative and test our drawing skills ;