A possible automatic door unlocker thingy?!

A 4.3GB IDE hard drive isn’t something people usually get excited over these days and with one just laying around here it wasn’t much use unless I wanted to chuck linux on it then forget about it. So I opened it up, along with a world full of oppertunity… well sort of anyway.

First thing to notice is the stepper motor… I am guessing it is low torque and high speed which could come in handy later down the track, the other thing is the write/read arm mechanism. Now this mechanism works off the same idea as a motor where you have a north and south pole and then an electric current running through the centre, causing crazy forces and stuff to turn it around… though in this case it is a bit different:

The large black sort of L shaped part to the right of the hard drive where the read/write arm disappears under is the part that acts as the North and South pole magnets… what you can’t see under it is the copper wire wrapped around the other side of the arm. Anyway, by applying an electric current through the copper wire allows us to control the direction in which the arm swings, by reversing polarity the direction is changed.

Now if 12v is applied the arm will swing to the opposite position with a supprising amount of force which got me thinking, dangerous i know but I thought all the same: This arm could act as some sort of lock mechanism.

All I have to do is work out what sort of lock it could be used for.

The Ramjet Project… Only the beginning?

For a physics assignment I decided to try to build a ramjet and that was about October last year. Now finaly, it has been built and tested and guess what? IT WORKS!… to a certain extent, but it works!Anyway for those who haven’t an idea of what a ramjet is check out this wiki page: http://en.wikipedia.org/wiki/Ramjet

Here is a quick model I made to show the basic structure of a subsonic ramjet:

And the ramjet I made:

As can be seen there are 4 main parts of a ramjet, the air intake nozzel, flame holder(also know as diffuser), combustion chamber and exhaust nozzel. Fuel (in this case LP Gas or Propane) is injected before the flame holder along with air traveling at high speeds, and in this case produced from a hair dryer and leaf blower.

The fuel/air mixture then passes through the flame holder which slows the mixture down and compresses it which is then iginited and is shot out the exhaust nozzel. The pictuer below shows the flame holder in my ramjet… in all its perfectfullness (is that even a word?), anyway you get the idea:

Now thats the basic theory behind how a ramjet works… here is some pictures of mine in opperation (i’ll try and post a video soon).

This is the flame that the ramjet produces when ‘idling’, as you can see it’s nice and blue but not much thrust is being produced, what is happening here (or so I believe), is that there is a good fuel air mixture being produced but for there to be any thrust the air being forced (by a hair dryer) into the air intake nozzel needs to be at a greater speed. Now here is a picture of the flame produced when the leafblower is started behind the hair dryer, causing a slight increase in speed.

As can be seen by the above picture there is a lot more oxygen that is being burn’t, hence the yellow flame, meaning the the fuel/air mixture isn’t as rich as when it was idling. To correct this problem I assume the amount of gas being injected into the ramjet needs to be increased, though on my fuel line from the LP Gas bottle I have a regulator… which I figure is ‘regulating’ the flow of the gas too much.

When the leaf blower is used by itself, it extinguishes the flame, meaning that the problem
is still with the amount of gas being injected… though taking the regulator of the line is a little crazy for someone of my experience at the moment…

Well I hope that educated you to some extent because it was certainly an educating experience… though I guess I had better do the whole responsible lecture now:

‘PLEASE DON’T MUCK AROUND WITH GAS AND FIRE!… GAS BOTTLES AND FIRE DON’T MIX AND SO DOESN’T GAS BOTTLE SHRAPNEL AND BODY PARTS! OH… AND I DON’T TAKE ANY RESPONSIBILITY FOR YOUR ACTIONS INSPIRED BY MY EXPERIMENTS SO PLEASE READ AND USE THE ABOVE INFORMATION AT YOUR OWN RISK!’

Okay… that should suffice…

Also please be aware that I am not an expert in this field and am an amateur when it comes to this stuff… so how I interpret the results collected may not be entirely correct though I do my best to make sure that they are as close to correct as possible. If you see a problem or disagree with anything that I ‘determine’ or ‘figure’ please make sure you let me know!

Anyway stay tuned for more crazy projects!

P.S If your interested in ramjets and want more ramjet projects to browse upon or simply just want to learn more, check out: http://www.pulse-jets.com/phpbb2/index.php