Posts Tagged ‘electronics’
Couple of questions came up as a result of my post and so after some additional measurements and thoughts, here’s the follow up:
I have measured the output of ADXL193 accelerometer with the Digital Storage Oscilloscope so here’s how it looks through time as read at the sensor location:
I have recently acquired several broken Swann Night Hawk SW231-WOC wireless security cameras and figured i would document the tear down process and anything interesting i might find. My goal in this project was to satisfy my curiosity, try my hands at fixing them and perhaps even learn something in the process.
Here’s how it starts:
And here is how it ends:
In this part I will describe the hardware side of the Punch Acceleration Sensor and the next part will be about the software.
You can download Eagle schematics and printouts here
Here’s the basic hardware schematic (click for pdf version):
These schematics use SparkFun Eagle Library for the Arduino board so the pins shown are for the Arduino board and not ATmega328. You can see how those pins correspond to ATmega328 pins by downloading schematics from Arduino Duemilanove specs page.
After practicing a bit with my makiwara and having a mind of an engineer I wanted to know how hard I am actually hitting. Plus I wanted to see if I can hit as hard from short distance (so called 1 inch punch) as with full swing. So that made me go on a frenzy searching spree to see if there’s anything out there and even what number should I be looking for – is it arm speed or acceleration or board speed? There are actually several studies done on the topic and many good articles written explaining the physics behind it. From what I gathered, a hand hitting a board can cause 200g of acceleration in the matter of 10 milliseconds. This gave me the parameters to look for and also the realization that there’s nothing out there that I could afford to buy. In my searches I stumbled upon SparkFun store and from there the whole world of ICs, microprocessors and electronics. So I have decided to make it myself and couple of months later (yes, things go slow when you don’t know what you’re doing :)) I present you the working product (sorry for the grainy video – needed more light):
I will limit this post to the general system overview and will follow up with post dedicated to hardware and another one for software. All code and designs will be available for free download and you’re welcome to do with it whatever you like.