Hard Drive Harvesting

A quick tip. Before you throw out an old hard drive, open it up and take a look – you could learn a thing or 2 and get some useful parts!

You’ll need an small hex screwdriver as these things aren’t really meant to be opened casually. For those as old as me, you might remember when you put a new hard drive into your PC you had to go into the BIOS and set Cylinders, Heads, Sectors etc – for your hard drive to work. Well when you open it up you might get a idea of what this actually meant.

The shiny round things are the platters – there can be many of these and the thing that looks like an arm of a record player is where the heads are. Each platter has two sides so there is a head for each side – so in my case this disk has 4 heads. On each side there are sectors and cylinders (sometimes called tracks).

Anyway – what I am after from this hard drive is the magnets they are super strong and quite useful for hobby projects or just any old crazy science experiment. Beware – they are super strong, so don’t pinch your fingers between them and they clunk together. They are hard to prise apart and it’s a good challenge to set the kids to separate them (the trick is to slide….)

In my picture the magnets are at the top right, I had to unscrew a fair amount of hex screws – but in the end they were easy to remove. My son took the shiny platters and they are going to be part of some sort of robot costume he is making!

harddrive2  magnets

When you are disposing of parts like this – please do the right thing and take them to the electronics recycling place (most councils have them) rather than just throwing them in the trash and adding toxins to landfill. Also remember to wash your hands after recycling. Note: The platters are quite safe to touch and re-purpose as long as you aren’t scratching into the material – they make great mirrors!

GCDuino+ Weather Station (WioLite)

This is a very light-weight version of the secluded.io Wio Weather Station using just an GCDuino+ (version of GCDuiNODE adapted for the ESP8266) and a few off the shelf components.

Data from the weather station is pushed up to Wunderground and you can see my station’s data at IQUEENSL506.

Components needed for this project:

  • GCDuino+
  • Standard Light Dependent Resistor (LDR)
  • DHT22 Temp/Humidity Sensor Module
  • Bosch BMP180 Pressure/Temperature Module
  • 2 10k resistors for pull-ups. You can use Arduino internal ones too if you want to risk it.

Wunderground does not support light readings (only UV and Solar radiation – and you need separate sensors for this), but LDRs are suitably cheap so thought I would throw one on there.

I used the following Adafruit libraries to read the sensors:

To get these libraries just navigate to ~/sketchbook/libraries and clone each of the libraries using the github urls in the above pages. I use SSH so my command line usually looks something like this:

One top tip when using the DHT library with the GCDuino+ and GCDuiNODE is to make sure you initialise the DHT like this to allow for slower clock speed:

I also cheated a bit with the DHT, so I could put it straight in on pins 11, 12, 13 and 3.3 I made some pseudo ground pins in software.

So far so good it seems to work fine – the protocol that DHT uses is digital so a slightly dodgy ground is probably passable!

Anyway – here are some pictures of the assembled board. For those with good eyesight you will see my very badly soldered SMD resistor between put 13 and 3.3v line on one of the pictures!



The code is still being updated a fair bit so I will post the entire code once I am happy with it.

I am not posting directly to Wunderground as their API is not the greatest, so I have written a small nodejs server that acts as a go between performing a few functions such as:

  • Metric -> Imperial Conversions (yes – Wunderground takes imperial data only on it’s API!)
  • Creating datestamp (Wunderground insists on a date/time stamp in API – not great if you don’t have an RTC)
  • Managing API Keys. Wunderground API takes station id and a clear text password (yes the only you also log in normally to the site with!) so I have replaced this with a generated API key that I map to a Wunderground user.

If you like weather stations, watch this space, the full version of Wio with rain gauge, wind and lots of other sensors will be coming soon!



Dalek sensor system

This project was created for the Gold Coast Science fair. It is basically a proximity detector that fires an “Exterminate!” through the speaker and lights up the gun when an intruder comes in it’s way. It was the most popular exhibit at the fair and the next phase will be to make it move!

This project was also documented and entered into the Hackaday Prize

Early Dalek Prototype


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