The Workbench

The Workbench
Making my Dreams a Reality

Monday, April 27, 2009

So what's been happening on the bench?

Been a while, these holidays haven't lent themselves to getting anything done.

Now the holidays are over, I have started doing stuff again, getting back into the swing of things.

So what have I done on everything...? Let me see, I have started building a CNC machine, Wired up the Go Kart, Built a wireless pair, Found a F&P Smart Drive motor, Updated to Ubuntu 9.04 (AKA Jaunty Jackalope), Build a water rocket launcher.

All that in one set of holidays :-O.

Sitting on my bench right now I have this:

This is the entire go kart electrics system. I also have a multimeter hooked up to read the temperature (max to date is 55°C). I got the battery pictured and another one, (same type), for free off a wrecker in Tirau. What I need to do is de-sulfate it. This involves building a circuit designed to de-sulfate. I will get around to it... The driver along with the MOSFETs does exactly as it should, and I am very pleased. The main problem at the moment is, because the battery is so old and crappy, I can stop the motor shaft with my bare hand. If I can stop it, so can the weight of the go kart right? After de-sufating the battery, it will be able to hold much more charge.

I mentioned earlier about the CNC machine. My dad saw the IT department of #####, (place of work), was having a MAJOR clean out. I scored a computer power supply (which is now dead due to unknown causes), 2 dot matrix printers, 2 scanners, 2 USB keyboards, a UPS, (Uninterruptible Power Supply), and two gigaset network phones (Can be made into walkie talkies).

Back to the CNC machine, inside the printers and scanners there were stepper motors, these stepper motors can be "stepped" by a computer. Each step is a few degrees. I have ordered some H-Bridge chips from ST Micro to control each motor (3 in total). I also realized I will need a controller for each stepper. The program I will use to control the CNC machine is called Mach3. This program has two wires per motor on the parallel port - step and direction. I will need to create an interface so the four inputs for the H-Bridge can be controlled by the two output pins on the parallel port. I have already found the driver, just a matter of building it.

I have built a new PIC Programmer, (maybe a PIC can be used for the driver...), same as all previous attempts. It is a JDM style progrmmer built onto a Kiwi Patch board from Andrew.

I haven't tested this yet as I have to revert to windows. I know there are linux programmers out there, but I really like icprog. Maybe WINE can be used instead.

Whats happening with the smart drive motor?

I will tell you. It has been rewired for 12v operation, and is currently being "decogged". This means I file each pole, (46 in total), into a nice curved shape. This will improve performance in low wind. I also have to build a new set of blades to drive the thing, it's much "chunkier" than all predecessors. Wood seems to be the best bet, but that will take a long tie, and I don't think I have all the tools to build them. So... Maybe I will have to give the PVC blades a try. I can cannibalize them from the six blade windmill.

Another project, yes another one! I am getting back into water rockets. After being inspired by George Katz from Air Command in Aussie. I have built the "Gardena" launcher, only I used a cheap aluminium socket from The Warehouse. The nozzles on these rockets are 9mm, giving more "burn time" than my older rockets (nozzle size of about 19mm).

Deal Extreme sells cheap Chinese crap. I found a nice cheap servo motor than will do the job nicely. By job I mean deploy the parachute. I have build a launch computer built onto a PICAXE 08M capable of pulling the pin on the parachute door. Previously I used the NSA, (Nose Seperates at Apogee), and this just sucked... I only ever had one success.

It was the greatest success of all time! There was a holiday program running at the park at the end of my street. All the kids had seen a couple of my launches, (failed parachutes), and decided to come outsude and sit down to watch. It was going to be my last shot of the day. I charged it up, pulled the string, and hoped for the best. To my surprise, and the the kids awe, the parachute deployed. It was absoloutely awesome to have such a big audience cheering away at something you yourself were amazed at.

Anyway, back to the computer. This computer detects launch, waits a short time, and then pulls the pin. This should be MUCH more reliable than old NSA...

Pictured is Version 1.1 Beta. I am currently at 1.2 Beta. Please note, the rocket has not yet left the ground.

Here is 1.0 Alpha:

In the real version, I do use the nokia battery. I have three old nokia phones, with batteries! I have used one here, one is on my bench, and one still powers a phone. I have soldered a jack onto the computer so you can recharge.

Wow, that was a lot to type. Guess that's what happens when you are as busy as me, and are too lazy to blog about it!

Hope you enjoyed reading =)


Thursday, April 9, 2009

Go Kart Controller

I have finished the hardware for the Go Kart Controller. It consists of the potentiometer, (for pedal location detection), the MOSFET array, (for switching), and the PICAXE, (the brain).

I haven't yet finished the code for the PICAXE. The program will monitor the resistance of the potentiometer. When the resistance rises, the motor will accelerate/decelerate and vice versa. To change the speed of the motor I will used PWM on the MOSFETs. I have tested this with an LED and it works just fine. The PWM in this case is at 10,000Hz. This means the circuit is switching on and off 10,000 times a second! The duty cycle is determined by the potentiometer.

These four MOSFETs are IRF1405. According to their data sheet they are capable of about 100A at about 100°C. Having four of them wired in parallel means I can have 400A at 100°C. Most sites I've been on state that starter motor current peaks at about 300A. 400A should be plenty enough!

Not much news on the data logger just yet. Bought some more parts of Andrew (wireless units!). I have NO idea how to get the Casio working... I've done it before, but it doesn't want to work just yet.

Sunday, April 5, 2009

All in a Day's Work

Today I did quite a bit on the go kart, not much on anything else. I tidied the bench just this morning. Look at it now!

Anyway, today I, with the help of my Dad :), re-did the case. I was hooking it up to the circuit, and the switch just kinda died... Bought NARVA brand gear. This stuff should last for years :-)



Much better huh? The weird texture was caused after a failed polishing. The dremel, (even though it was a cloth pad), really dug in. Polishing compound was stronger than I though.

Also on the bench is the datalogger, haven't made ANY progress... Tried to hook up the calculator to 28X1, harder than it was first time around I can tell you!

In The Future...
Hopefully my part, (RTC), from wherever in the world it's coming from arrives soon. I'm also waiting for the four MOSFETs from Ross. He had to order them in from Jaycar, so I'm not too surprised it's taken a little while. Sick with some weird illness ATM, so I'll get a bit of progress on this project while I'm home. Was hoping to buy Crysis, but I'm not keen on leaving town... Would have been good though :-). My Dad is pretty keen on it, so I'm sure we'll get it soon.

Enough from me for this post. I'll write another post when stuff strats arriving :-)

Thursday, April 2, 2009

Quick Update


The board will fit just fine. I was planning to buy it this weekend, and decided not to due to size limitations, but this box it over kill :-).

Just so you know, this box is on clearance, so is cheaper to buy this than the size down (about $3 less).

The Electrical Update

Data Logger:

I have, (as you know), ordered the Real Time Clock chip, and a few parts from Andrew H. Yesterday the coin cell, and the coin cell holder arrived from Andrew. I was so excited I didn't want to wait for the RTC from wherever in the world it's coming from, so I built the circuit all ready for the chip to be plugged in.

The clock carrier board can bee seen on the left, next to the 28X1 main board. The red wires lead to the socket for the casio lead. I haven't figured out how to do it yet, but I will. It involves some careful timing.

Go Kart Motor Driver

Was off sick from school today, (Gastroenteritis the Doc thinks), and priced up the bits and pieces I need for the enclosure. I'm planning to use a sealed polycarbonate project box. It has an IR68 rating, meaning that is is 100% dust proof, and Waterproof below 10m. I don't need it to be this good, but it will be good to have protection from the weather.

Anyway, the total cost of the parts comes to $34 from Jaycar, and $21 from DSE. I still have a $20 Gift Voucher for DSE from August last year! It's easy to see where I'll be buying the parts from. The problem is, you can't buy the case until AFTER you build the circuit. I'm not going to buy the case only to find nothing fits now am I...

The circuit will be build onto one of the KiwiPatch boards from Andrew. He has a great deal where you can get one free for every picture you post of one with a project. I have, let me count), six boards. I haven't claimed many of them either, (three in fact), so it won't be hard to increase my collection as needed. After this post I plan to measure the size of the board and compare it to the dimensions of the box. Fingers crossed.

More news next post :-)


Me and my sister recently bought a pet rat each. I named mine Samantha, and Sarah named hers Lilly. We have just finished building them a new cage out of two run-of-the-mill pet store cages. It involved removing the top of one, the bottom of another, and cable tie-ing them together.

For two rats, I think the cage is PLENTY big enough!

Jack also bought Rats, so if ours, (or his), need somewhere to stay, we have it covered.

Mum absolutely adores these two, and can often be found either; With the Rats, making something for the Rats, or on the best Rat site on the net (The Dapper Rat). Just today she made them a sleeping bag from a fleece blanket, and an old towel. Thanks Mum :-)