3D Printed Lever for AirPax Circuit Breakers


This is a very specific project, but I’m writing about it anyway in case someone has the same problem. I own an old boat, with an old switch panel that has old circuit breakers. Needless to say these particular breakers are not made anymore, but they still work well. Except the levers have a nasty habit of breaking. Continue reading

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Cheap Temperature Gauge for a Boat Engine

IMG_8207Here is a good idea I saw for cheaply monitoring engine temperatures. If your boat engine has ever overheated (like mine has) you will be a little paranoid about watching the temperature. I found some cheap digital thermostats on eBay and mounted them in a enclosure. The temperature probe wires needed extending, and I wrapped them in heat shrink for extra protection. I strapped one to a metal elbow in the cooling circuit, and the other to my exhaust, just after the raw water is injected. They can be powered from the engine ignition and will display the temperature of the probe. With a few buttons, you can programmed the thermostat to trigger its relay if the temperature goes beyond normal operating range. The relay is connected to a buzzer, acting like an over-temperature alarm. Works great!

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Building a NMEA 0183 Wind Instrument

isailor_windUPDATED 09/08/2016. Following on from the last project, where I broadcast NMEA GPS data to iSailor, I wanted to send wind measurements as well. The mast in my Westsail 32 was out, and it was a perfect time to put a new wind vane on. The app iSailor now has an unlockable wind instrument display, meaning I could channel the measurements straight to it. Alternatively I could also send the data to a laptop running OpenCPN. Firstly I needed a wind vane to mount. In the same mind as the excellent Freeboard project, I decided to use a Peet Bros. Anemometer to mount at the top of the mast. The unit seems extremely reliable and simple, having only two magnetic reed switches inside. The timing between the switch pulses gives wind direction, and the frequency of pulses gives wind speed. It really doesn’t get much simpler than that, and this set-up only requires three wires to be run up the mast (eg. an audio cable).

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Getting NMEA GPS data in iSailor


If you have been using the iPad app ‘iSailor‘ for navigation (as I have), you may have seen the option to unlock NMEA positioning support. NMEA-0183 is a standard protocol used to communication marine information such as depth, speed, position etc. Most off the shelf GPS modules use this protocol as well. So I investigated how I could get my non-GPS enabled iPad (ie. non-cellular) receiving GPS data from another source.

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Building a JGRO CNC Router


To enable further projects, I decided a while ago that building a CNC router would be a great idea. This would allow me to cut wooden bits for projects and engrave circuit boards. I decided on the tried and tested JGRO plans, available for free on CNCzone.com. The JGRO design is mostly made from MDF, which is cheap and easy to cut at home. It also features metal pipes and skate bearings for the linear rails, which are simple and cheap but subject to slight flexing under load. Still, for a cheap home built machine, this is not too much of a problem. Continue reading

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GPS Sailing Data

Having recently purchased a Hobie 14-ft catamaran, I have been having fun out on the water, but also wondering how fast I’ve been going. To give myself some idea, I decided to make my own instruments using an Arduino, LCD and GPS.

Sail Log

My first prototype is shown, displaying the speed in knots (0.0), the current compass heading (111°), the time, number of satellites (07), and the battery voltage (412mV). If you add on an OpenLog from Sparkfun, you can save all the GPS data to a flash card for viewing on a computer later. Best of all, it’s really quite easy to make! Continue reading

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Robot Prototyping 101


Over the past few years, the back of my mind has been thinking about a small, quick, camera robot I could drive around. Recently, with the help of a 3D printer I was finally able to print a chassis and put one together quickly. Continue reading

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3D Printed Phone Holder

phone_holder2I decided to try my hand at designing and 3D printing a phone holder using Solidworks. Two prongs on the back allow me to attach it to a car’s AC vent, and the thread on one side allows it to be mounted on a tripod. Designing it myself allows the phone and case to fit snugly.

I printed it out in ABS plastic at the Techshop in about 3 hours. The phone fits pretty well, but it’s a little loose. In the next iteration I can tighten up the tolerances.phone_holder

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MIDI Keyboard Visualiser

A while back I bought some cheap, multi-colour LED modules on ebay. I’m not sure what they were designed to be used for, as each time power was applied they cycled through different colour combinations. The modules had an AT89C2051 microcontroller on the back which would be too bothersome to reprogram, so I decided to do a bit of reverse engineering and control each module externally.


My idea was to create a MIDI controlled array out of the modules, to visualise the notes coming from a piano keyboard. To do this I removed the microcontroller on each module and mapped the circuit layout to find the control lines for each group of LEDs. I decided to build an array of 3 x 4 modules, 12 in total to match the number of semitones in a (western) musical octave. So 12 modules * 3 colours per module = 36 outputs to control. To control this many I ordered some free samples of the TLC5940 from Texas Instruments, which is a 16-Channel PWM LED Driver. With three of these chips I could control up to 48 outputs, more than enough!

For the brains I ordered a ATMEGA 32U4 board from Sparkfun. The nice thing about these boards is that they come with a USB connected bootloader, making them super easy to program with AVRDUDE. The only trick was using the board’s ISP header to reprogram the fuse settings.


To drive the TLC5940 chips, I found an excellent C library and notes written by Matthew Pandina. I then needed to build a MIDI input circuit and connected it to the ATMega32’s UART RX pin. There is a great article on interfacing MIDI signals to and AVR on avrfreaks.net. Next came writing code to put it all together and map MIDI notes to particular LEDs.

The initial source code I’ve written is available here. There are still some bugs so use it at your own risk! Here it is in action:

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Let’s Go Sailing Automaton


Being inspired by these AMAZING DESIGNS by Wanda Sowry, I decided to design my own automaton with a sailing theme. My first version was a failure. It was overly complicated and had too many gears. So I wrote it off as a learning experience and started afresh.


After a few rough sketches of what I wanted, I used Solidworks to create the design and model each part. I could then define how the parts moved and interacted with each other, to refine the design and make sure it would work. It was then a matter of exporting each piece to Corel Draw so they could be cut on the laser cutter at my local Techshop.

The fun part is painting, assembling and gluing all the pieces together. I made plenty of notes too on how the design could be improved and what tolerances work best. With everything assembled and working, I just need to show it off!


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