Whitterm-220 Clever Serial Terminal

The Whitterm-220 (WT-220) is my latest project. It’s a clever terminal, in the sense that it aims to emulate the dumb terminals of the 80s but with the versatility of something produced now. The name comes from my inspiration for the project: failure to win a VT-220 on eBay. I decided it would be fun to make a homage to the VT-220, that would actually be useful – a not so dumb, or clever terminal – that would do more than simply parsing RS232 levels into Ascii characters.

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Nixie Tube Energy Meter

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Having recently bought a house, project time has been a bit thin on the ground. As a standard terrace house, the consumer unit and electricity meter were in the entrance hallway, exposed and looking a bit naff. I liked the look of the meter so I quickly created a box that allowed the meter to poke through and leave access to the fuses.

The box covering did the job but felt a bit cumbersome with all that spare space; it needed something else to give it more purpose. An energy meter was the obvious thing but I didn’t want a garish LCD or 7 segment display, it need to match the blown glass electricity meter… …nixie tubes!

The Nixie Module runs off 5V and SPI
The Nixie Module runs off 5V and SPI making the project quick to get off the ground

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Noise Crayon – Noise Amplitude to Light Spectrum Converter

Continuing on from my Ambient Noise Level Indicator, I wanted to create an enclosure and make it stand-alone – not requiring a computer to do the processing. I ended up with a little device that converts noise amplitude to the light spectrum: Noise Crayon.

The Ambient Noise Level Indicator used the MCU serial host Processing to perform a FFT and various averaging routines to create an indicator for ambient noise. The idea being that it would change colour when background levels rise above a threshold. Moving to an ATMEGA328, performing this processing – especially the FFT – is asking a little too much of it. There are libraries but I’ve heard of limited successes.

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Wooden Bits – Binary Clock

Wooden Bits Gif

I’ve been meaning to make a binary wall clock for a while and to also try out kerf bending with the laser cutter. What put me off creating kerf bends before I found OpenSCAD, was the manual creation of all the lines in the right places. It’s the kind of repetitive, uniform task computers were made to do.

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MATLAB Finite Difference Time Domain Acoustic Modelling

As part of MACH Acoustics’ open window research, they wanted a FDTD model to visualise sound waves moving through various window opening scenarios. I created a FDTD function, that would create an impulse wave at a specified position then calculate discrete pressure points across a defined grid size and time step. Geometry (boundary conditions) could be loaded loaded into the function using scripts for different objects (opening, top/bottom swing window, baffle, etc), video saved and pressure, mic, time step data saved for repeat plotting (the solver took a few minutes to run so being able to plot existing data saved time). There is no currently no absorption so the sound does not decay, reflecting 100%. For short periods however this does not hinder the visualisation too drastically.

A GUI I created to control the simulation settings.
A GUI I created to control the simulation settings.

The videos below show it in action.

Opening with internal baffle plotted in isometric using surf

Opening with internal baffle plotted in isometric using surf

Laser Cut Battery Powered Bluetooth Speaker

I wanted to create a special birthday present for my girlfriend, whom had no speaker system. I decided a battery powered Bluetooth speaker would be neat, and having just learnt use of the laser cutter I came up with a layered design.

I created a mock up in SketchUp, which I used to visualise the layers together and make sure it would work.
I create a mock up in SketchUp, which I used to visualise the layers together and make sure it would work.

The internals consist of a 2x15W RMS digital amp, 2x15W 80 cones, a Bluetooth module, 1800mAh NiMH battery and a basic fast charger – plus a few voltage regulators to bring everything together. It’s all wired so that you can charge while plugged in and still play, and turn the Bluetooth on and off. Finally it’s all insulated with sheep’s wool I had left from doing my van. I found the insulation helped reduce reverberation (probably due to the thin layers) that muddied the mid-ranges. One thing I like about it is that the front and back can be easily changed: the front grill pattern to change the look and the rear could be tuned to include a bass port for better bass response.

I fairly pleased with the result and might start producing them if there is enough interest.

FYP: MATLAB A* Based Path Planner for Autonomous Off-Road Vehicle

A picture says 1000 words

Synopsis

A new venture for the University of Bath and a collaboration with Mechanical and Electrical Engineering, the autonomous quad project aims to convert an ’off the shelf’ miniature quad bike to a driverless one. Generation of a least cost path to a pre-defined goal is required, which avoids known obstacles and will update for new obstacles detected during driving. The A* search algorithm is chosen and a comprehensive planner developed within MATLAB.
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