The Bench-top Power Supply

So here is yet again another infrequent post in this mess called a blog. If I was a reader of it I would have lost interest long ago and forgot the address to this site but then again I am just one of those impatient sort of people. Yet with this in mind I do endeavour to be a little more constant with my posts. I have tried to make things a little bit more interesting by adding a new section which has got some of my photography of aircraft and aviation in general which I hope you enjoy.

Anyway by now you are asking why I named this post The Bench-top Power supply so I’ll get straight to the point: I needed something to do… so I made a Bench-top Power Supply. There are plenty of other things I could of made which would have been much more stimulating and interesting but the fact is having a variable power supply is so handy and I would add a few small features which I find come in handy.

I have used a standard step down transformer (240 VAC to 15 VAC), a bridge rectifier kit and a voltage regulator kit from Jaycar (www.jaycar.com.au). So thats the basic idea to a power supply, I then added terminals to plug in a dc supply to be regulated (i.e. Car battery) and a toggle switch to select between the ac and dc sources. I then added a tie switch which allows the power supply to be either floating, positive tied to earth or negative tied to earth. Call me lazy but it saves the extra wire to do the tying for you.

I hope to be a little more frequent now with this blog but no guarantees as I’m coming to the end of my avionics course so I’m a little busy. Anyways, Enjoy.

The Digital Harp…

This little project has been in the making for a couple of weeks now and finally it is completed, so here it is and I hope someone out there can find this information helpful atleast.

So what is the digital harp? Well the idea evolved from a thought train of creating a dynamic and complex music instrument that could be controlled by the fingers yet while not touching a single string/key/button/pie and produce a vibrant and beautiful sound. So after a bit more thinking I came up with a compromise to my ambitious thoughts and
managed to bang together a digital harp consisting of four “digital” strings, a ukulele and a very very simple synthesizer.

So very simple.

Using four LDRs and a voltage divider circuit which a transistor sensing the increase in voltage drove a solid state relay I was able to create a very small and easy control circuit for when a hand moved in front of the LDR and blocked its light source from the laser.

I created the oscillator using a 7414 chip which is a Hex Inverter with Schmitt trigger inputs and put a resistor in between the input and output legs and a capacitor. This oscillator provides a square wave output, unfortunately square waves don’t produce the best quality sounds but for this project it worked okay, though if you have the time and the parts I would recommend building a sinusoidal wave oscillator as they sound a lot better.

I setup four of these oscillators for each of the digital strings and then their outputs into the one amplifier.

This is the square wave oscillator setup:

Then its just fitting everything together onto the ukulele which was basically done using a hot glue gun. I removed the nylon strings and tuning pegs, put a on/off switch on the side with a LED… its not a real project if there are no LEDs, and fixed a 6.5mm audio socket to it as well so I could plug it into my guitar amplifier.

I haven’t drawn up an official schematic yet but I do plan to in the near future… if anyone is interested in it let me know, it might just help with motivation.

There are a few little problems with it at this stage but it is practically working as expected and is a great little tool to annoy friends.

Until next time!

Finally… A combination lock!

For about a year now I have been wanting to build a combination lock with the PIC16F84A so finally here it is, very simple as it is yet the important thing is that it works.

I built it from the schematic from this website: http://jap.hu/electronic/combination_lock.html:

The hex and asm code can also be downloaded from the website to program the pic with. For this initial setup of the combination lock i made a few modifications to the design which involved taking out the 5v regulator and replacing it with a 5v1 diode, removing the relay and transistor setup and replacing it with a simple L.E.D and also getting rid of LED1. The crystal I used was a 3.578 MHZ crystal. The main purpose for all this is just to make sure the PIC is being interfaced with the keypad correctly and is acknowledging a password being entered in and being able to change its password stored in its memory. Which, believe it or not – works! <insert a little dance here>

So now that everything looks dandy on a basic level the goal is to have a combination lock that is interfaced with a computer, allowing a number of parameters of the lock to be changed via pc as well as passwords and a log of what has been entered on the keypad and any successful or unsuccessful entry attempts. Anyway thats hopefully where things are heading!

Stay tuned for more mystical, world domineering and pointless projects.

A laptop without power is not a happy laptop

This time not a pointless project and for that I am so sorry but I feel that it may be of some help to others who come across a problem similar to this one. The problem was an Acer Aspire 3681WXMi whose battery didn’t charge and wouldn’t run off external power… now there is obviously only a few things which could have been at fault in this case: 1. Power Supply 2. Power Supply Socket on Motherboard or 3. Motherboard. Now skipping past all the testing and troubleshooting it turned out to be the power supply socket on the motherboard and wahoo! to any Australian who can get a replacement locally. In the end I decided to go for the quick fix which essentially works anyways so long as you aren’t in for any flashy look.

I took to the socket with a pair of pliers, then made my own beautiful plug <insert the rolling of eyes>.

So there we have it, not the prettiest repair but it works.

Also just a couple of things to note with the blog, some of the images are not being displayed due to their hosting being closed down so I hope to have them re-hosted soon.

Apart from that hoping to have some more stuff up here soon!

Ultimate Desktop Fan x5000

I guess, readers, you were all waiting for a new innovative technical breakthrough after I being away for so long yet I have come back with something much more cooler… A desktop fan.. taking exactly 20 minutes to build and minimal thinking power. Here it is:

Simply a computer cpu fan hooked up to 9 Volts or it can also handle 12 Volts. The great thing with these fans is that they are made to be running for great lengths of time – my computers fan runs 24/7, 365 days a year and hasn’t died yet. The only thing to remember when setting it up is to make sure the air will be blowing towards you and not away.

So there you have it folks,

Enjoy!

Zane Vohland

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.

Controlling an RC Car with PC

My apologies to all you fanatic readers out there who have been waiting for an update… (I think I am talking to an empty room…), but oh well, here is an exciting update! WAHOO! (insert rolling eyes here):

Inspired by Mr. Ashish’s little project (ashishrd.blogspot.com) of controlling his remote control car via the computer, I decided to try to the same to my remote control car and hook up my wireless camera to it as well.

So I guess it all started with my brothers remote controlled car that was laying under his bed collecting dust.

From there the idea evolved into a question of can Ruby programming language be used to control the car? Well of coarse it can! I mean, its Ruby we’re talking about here. Though the initial search on the subject seemed to turn up nothing in particular, I was mainly wanting to know how ruby when about detecting a key press. So search I did until I found this peice of code:

So it was a start… from there I just mucked around with it until I got it to eventually work. I then wrote up some if statements to check weither or not the key was pressed and if it was what the program was to do, so for example if W was pressed send 0001 to the parallel port. Now for an interesting fact: I have always heard people, when talking about programming, discuss effeciency of the programs design and how much fast the program can run if it is structured in a certain way, now I had never came across that in my mild dabblings in programming until this day; With my program all written up I then tested it by pressing up, down, left and right but there were slight pauses in the program and it would detect the left key unless you pressed it a few times and the same with the right key and I had a weird feeling it was to do with the if statements… so I changed it all to a case statement and everytime no matter how fast I pressed each key and in what order each keypress was detected… very interesting!

Now that I had that under control, the car’s controller had to be interfaced with the the computer. I happened to have four relays laying around at the time so I used them and found a nice little schematic that helped things, I just modified it to my needs:

Also instead of the BC548 I just used 2N222A’s and I didn’t bother with the resistors… everything seemed to work fine without them… this is how the whole thing turned out:

And here is a picture of the RC Controller cracked open and a few wires soldered here and there:

And so after a successful afternoon of soldering and programming it all worked fine… here is the car with my camera attached and ready to allow me to experience the great outdoors from my computer… oh I am lazy!

Remote 360 Camera Panner

Well as bordem strikes, one finds themselves looking for ways to quench their thrist for ultimate knowledge of all things of the universe… but only when bordem strikes. Otherwise we would be doing more important things like working, cleaning and all of that sort of stuff. Anyway in my seeking of the ultimate knowledge of all things I happened apon my RC Plane’s electronics which I had brutally gutted from a flimsy, plastic excuse for an aircraft.

Believe it or not, multiple crash landings for these planes do them no good… funny that, isn’t it? In the end I think the nose of the plane was closer to the centre of the aircraft than was to the front.Now, what comes out of those cheap little RC Planes is quite interesting, for $50 – $100 AU you get two mini servo’s, a motor speed controller (miniture size) and a 4 channel reciever… not bad at all, and think of the possiblities! Now I went back to my mini wireless camera and got to work making an extreme 360 Degrees Panning thing.

It was all pretty simple and no great electrical knowledge was required, all I had to do was replace the high speed and low torque motor that came with the RC Plane kit with a low speed high torque motor and it was done and with a little bit of mechanical handiwork I rigged up a couple of PVC tubes and a blank cd holder, to allow the camera a base to swivel on.

It worked perfectly. Not a completely useless project completed, WAHOO!.

A Nice Car and A Pic Programmer… What more could you want?

Well, I have something slightly different for all you fanatic readers out there and its to do with graphics, but have no fear I also have included some electronics at the bottom of this post as well…

Anyway today I opened up my laptop to find I had photoshop open so I though why not try my hand at something graphical today?… so I figured if Car Photo + Imagination = Imagination Car Photo then I should be able to do something rather interesting and here is what I came up with:

A nice Holden Monaro… The original photo is from http://www.carpw.com/vauxhall+cars/monaro/vxr+(2005)+170/?1

And here is a nice before and after:

So now for some electronics,

I have just moved my Pic Programmer which I built not long ago from the prototype board and put it all in a nice case and everything:

I have made it so that you still have to use a prototype board to hold the PIC but all I have to do is connect it up to the 5 wires on the cable, this is so I don’t have to worry if I want to program a PIC with a different amount of pins.

Also in my previous post about regarding PIC Programming I mentioned that my initial problems were due to a faulty serial cable but I was wrong… I bought a new serial cable and it gives the same readings as the ‘faulty’ cable. I have came across a serial port power booster that can be made using a MAX232 chip I will have a go at making, and will hopefully fix my voltage problem.

On other news I have been mucking around with a 3×4 keypad and PICBasic as well as giving my self crash courses at Assembly. So far I have got the circuit to beep everytime a key is pressed… stay tunned for more exciting info on my progress of making the most advanced combo-lock the world has ever seen!

Blinking an LED with a PIC16F84A

After building my Pic Programmer I needed to do something with it, so now I present to you…… An blinking LED controlled by a PIC16F84A (I suppose this has been done to death but hey, you gotta learn to walk before you can run)…

So I done some searching for a nice tutorial on programming a PIC to flash/blink and LED and came across this tutorial: http://www.mikroe.com/en/books/picbasicbook/01.htm

It provides a schematic as well as the code needed to program the PIC which is handy.

Unfortantely I didn’t have any 4MHz Resonators on hand so I just used a 3.5MHz crystal and 2x 20pf ceramic capacitors instead and also I left out the 10K Ohm resistor going to the /MCLR pin and used a 150 Ohm resistor on the RB7 pin of the PIC (before the LED) and my power supply was just a 5v, 800mA powerpack.

I downloaded the mikroBasic Compiler from the website also and it seems to be a nice decient free compiler which I recommend try out.

Anyway, after compiling the code (I tried to use the hex provided but it didn’t work so I ended up just compiling the provided source code) and plugging it all in… it works!

I have a 3×4 keypad laying around here somewhere… I think I will see what I can do with that…