J44 Industries

Proton Pack 2011

2012-01-04T13:07:00.000-08:00

Latest Proton Pack Upgrades:

Bouncing Soap

2011-08-14T07:21:00.000-07:00

A fun simple experiment.

Inspired by the Naked Scientist kitchen science experiment :
http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/bouncing-soap/

Airow Gun

2011-01-30T15:30:00.000-08:00

An Airow gun that I got recently.

The mountings that came with it were not the right size for my recurve so I used polymorph to make a custom bracket and some cable ties to hold the whole thing together.

QR Code

2011-01-30T14:25:00.000-08:00

Instructable

Ghostbusters Proton Pack

2010-11-21T14:12:00.000-08:00

Ghostbusters Costume

My MkII proton pack for Halloween 2010.

I made a Ghostbusters costume a few years ago and it was great fun to ware, but knew I could do better so this is the MkII. There is a lot more I would like to add (maybe next year), but it will do for now. The costume got me stopped by the police (so they could take photos) and drew a crowd on the train.

MkII now with lights, sound and smoke.

Electronics used:
Arduino for lights- http://www.arduino.cc/
SparkFun mp3 sound effects board- http://www.sparkfun.com/commerce/prod...

See the video after the jump.

District 9 inspired model gun

2010-11-21T13:42:00.000-08:00

A District 9 themed model gun.

It was an experiment in using foam as a modelling material as well as seeing if I could remember how to paint.

Inspired by the brilliant instructable
http://www.instructables.com/id/How-to-make-a-district-9-Weapon/

Arduino thoes Callipers

2010-06-29T15:47:00.001-07:00

Reading Digital Callipers with an Arduino / USB - More DIY How To Projects

Talcapult instructable

2010-06-17T15:27:00.000-07:00

Explosion Effect - Talcapult - More DIY How To Projects

Jdog Testing video

2009-12-03T14:58:00.000-08:00

Early testing of the Jdog system

Demo of air (well almost) and ground targets.

Jdog is reading PWM output from the standard RC receiver, so is fully remote control.

Range of the jdog is not very impressive yet, but that is an easy problem to solve with a bit more power and some lenses.

Duino Tag news

2009-11-13T12:25:00.000-08:00

I have finally completed my Duino Tag instructable.

Arduino Laser Tag - Duino Tag - More DIY How To Projects

Arduino Frequency Generation

2009-09-30T05:19:00.000-07:00

Probably a useful read for anyone trying to accurately generate frequencies in the kHz range using an arduino.

I need to accurately produce 38kHz signals for IR communication projects.
Not all pins give the same frequency output for the same code.

Results in brief: avoid PWM pins if you are not actually using the PWM feature.
In my code instructions took about 4microseconds per half wave form cycle.

Full results after break:

Code Used:

// Frequency Testing: extract from upcoming arduino Miles Tag code.
// http://j44industries.blogspot.com/

// Signal Properties
int IRpulse = 600; // Basic pulse duration of 600uS MilesTag standard 4*IRpulse for header bit, 2*IRpulse for 1, 1*IRpulse for 0.
int IRfrequency = 38; // Frequency in kHz Standard values are: 38kHz, 40kHz. Choose dependant on your receiver characteristics
int IRt = 0; // LED on time to give correct transmission frequency, calculated in setup.
int IRpulses = 0; // Number of oscillations needed to make a full IRpulse, calculated in setup.
int header = 4; // Header lenght in pulses
int maxSPS = 10; // Maximum Shots Per Seconds. Not yet coded in.
int TBS = 0; // Time between shots

int IRtransmitPin = 13; // Primary fire mode IR transmitter pin

void setup() {
Serial.begin(9600);
pinMode(IRtransmitPin, OUTPUT);
frequencyCalculations(); // calculates pulse lengths for desired frequency
Serial.println("Ready");
}

void loop() {
sendPulse(IRtransmitPin, 10);
}

void sendPulse(int pin, int length){ //importing variables like this allows for secondary fire modes etc.
int i = 0;
int o = 0;
while( i < length ){
i++;
while( o < IRpulses ){
o++;
digitalWrite(pin, HIGH);
delayMicroseconds(IRt);
digitalWrite(pin, LOW);
delayMicroseconds(IRt);
}
}
}

void frequencyCalculations() {
IRt = (int) (500/IRfrequency);
IRpulses = (int) (IRpulse / (2*IRt));
IRt = IRt - 5;
// Why -5 I hear you cry. Answer it just worked best (on Pin 3) that way, presumably something to do with the time taken to perform instructions

Serial.print("Oscilation time period /2: ");
Serial.println(IRt);
Serial.print("Pulses: ");
Serial.println(IRpulses);
//timeOut = IRpulse + 50;
}

Results:

Half time period delay: 8 Micros
Theoretical Frequency (instructions executed infinitely fast): 62.5kHz

Same for both a roboduino Nano (168 chip) and Arduino Dumilnove (328 chip).

Pin Frequency (kHz)
D2 : 40.94
D3 (PWM) : 36.94
D4 : 40.94
D5 (PWM) : 38.00
D6 (PWM) : 38.18
D7 : 40.94
D8 : 40.94
D9 (PWM) : 38.93
D10 (PWM) : 38.75
D11 (PWM) : 37.12
D12 : 40.94
D13 : 40.94

Conclusion:
Do not use PWM pins and reduce half time period by 4 micros for accurate frequency replication.

Canon Compact Camera Remote

2009-09-20T05:16:00.000-07:00

I made a remote for my Canon IXUS950IS camera.

The remote works with Canon compact camera's only as the camera needs to have CHDK installed.

Remote gives both a remote shutter button at the end of a USB cable and allows for any IR remote (eg TV remote) to be used to wirelessly trigger the camera.

Links:
CHDK: Firmware add-on for Canon compact cameras.
CHDK Remote details.
Instructable for the remote.

Talcapult and Duino Tagger demo video

2009-09-17T11:33:00.000-07:00

A video to demonstrate the talcapult (full details and designs to be released soon).

Video also features my Mk2 Duino Tagger.

Super Secret Agent Laser..........

2009-09-16T16:55:00.000-07:00

Inspired by the awesome Big Bang Theory.

All you need is:
Green laser
Arduino
Small photovoltaic cell (solar panel) attached to an arduino analogue input.
Peizo buzzer - arduino digital out
Small mirror tiles bluetacked all around the room
Spray smoke (try maplin)
Battery to power your arduino

JDog Progress

2009-09-16T16:35:00.000-07:00

JDog (J44 RC Dogfight System) Progress Report:

Prototype board has been soldered up.

Works well so far. Have had to re-think methods of reading PWM input form the receiver. Just need to write the arduino code now.

Prototype PCB's

2009-09-16T15:19:00.000-07:00

Making of the Jdog (J44 RC Dogfight system) PCB's:

After several attempts and plenty of learning by trial and error the best way I found (I make no claims to be an expert, so do not consider this a definitive guide) for making custom PCB's was:

Using Pre-Sensitised copper-clad board from Maplin (sensitised to UV).

Print off PCB layout (designed on KiCad) on OHP paper.

Double up layers of OHP printed PCB design. This prevents any scratches or marks on the design on one of the layers effecting the finished PCB.

Padded the inside of a CD case and used the CD case to hold the OHP paper and PCB in contact.

Exposed the PCB with a 4W LED array held about 0.4m away to give an even exposure.
An exposure of about 15 min seemed to work well.

Develop with Sodium hydroxide (1teaspoon NaOH in about 250ml of water), use a soft paint brush to brush off the developed mask. Mask developed very quickly (about 1-2 min).

Patch any breaks in the etch resist with an etch resist pen.

Etch the copper (with ferric chloride), use a sponge (dab more etchant on areas etching slowly) to ensure the PCB develops evenly. PCB took about 15min to etch (I suspect the etchant I was using was a bit old, may be a bit quicker with fresher etchant).

Clean PCB.

Note: Take care with the Sodium Hydroxide and the PCB etchant.

Recurve Basics Poster

2009-09-14T14:23:00.000-07:00

An archery poster I designed and intend to sell if there is sufficient interest.

Poster shows the basic parts of a recurve bow.

Recurve Technical Poster

2009-09-14T10:42:00.001-07:00

An archery poster I designed and intend to sell if there is sufficient interest.

Poster shows some of the important dimensions on a recurve bow.

Status of RC Dogfighter systems

2009-09-14T09:30:00.000-07:00

Prototyping stage:

Currently I have some custom PCB's waiting to be soldered up and tested.

The arduino code needs to be written.

I also need to come up with a good design for the smoke unit.

Talcapult: Introduction

2009-09-14T08:49:00.000-07:00

Why/What?

In brief: A cheap way of making things look like they have just exploded.

Aim: Cheap, safe, more flexible alternative to pyrotechnic systems (not that I don't love blowing stuff up, I just can't afford to most of the time).

How it works: It catapults talcum powder into the air which quickly disperses and looks like a mini mushroom cloud.

This project is a spin off of the RC DogFight project.

The talcapult is placed on the ground and reacts to IR. When it detects a hit either from a Duino Tagger or a RC plane mounted IR tagger system it will launch talcum powder into the air giving a mini mushroom cloud.

Multiple units could be controlled by a single arduino.

The project will allow for a much more interesting laser tag / duino tag / RC dogfight game: Adding visually impressive "explosions" to the games.

Imagine your JDog equipped RC plane swooping in on a few model tanks, picking a target and shooting, then seeing the explosive cloud billow up as you shoot it.

About

2009-09-13T16:48:00.000-07:00

About Me:

I have started this blog in order to share information on some of my various engineering and design projects.

Hope some of the info on this site will help others to enjoy engineering and science as I do.

Interests: Archery, RC models, Hovercrafts, Outdoor pursuits, the open source/creative commons world.

Background: I have a general engineering science background, but have always particularly enjoyed electronics projects.

Sam

j44industries@googlemail.com