Thursday, 3 January 2019

A 3D-printed mount for a ham radio whip antenna

New year, same me, new blogpost (finally).

In the last few months I've gained access to a Makerbot Replicator 2 3D printer and I've been spending a bit of time acquainting myself with it, printing test pieces, understanding the slicing software, and exploring the Autodesk Fusion 360 application for design.

I have a tunable whip I occasionally use for portable QRP (low power) ham radio operating - a Wonder Wand Widebander. This is designed to attach directly to the back of a portable radio such as the Yaesu FT-817D using its RF connector. However, a number of my radios are kit-built or homemade and don't have a suitable mounting point, and I'd like to use a cable to connect the antenna to those radios - a support was therefore needed for the antenna.

I spent some time over the holidays putting together a design for a bracket for the antenna that would mount onto a standard camera tripod, and printing the first instance. A recess in the bottom of the bracket accepts a push-fit 1/4"-20 UNC nut that the tripod screws into. Photos below.

Files for the print are available on Thingiverse including STL files for printing and a Fusion 360 archive for modifications.

Monday, 11 April 2016

Big Clock: building a MIDI Master Clock, part 2

Back to part 1

The Electronics - design and layout

In this project, the electronics design mainly consisted of hooking up devices to the input and output pins of the Teensy. Although I mainly use the gEDA suite for schematic capture and layout, this time I used KiCAD as an experiment. My first cut at the schematic is shown below; MIDI interface is driven through hex buffers to provide the necessary drive to meet the spec requirements, the display is hooked up with the SPI interface, pullups are added where necessary and I’ve added a couple of low sided drivers to the LEDs to level shift up to the 5V supply the LEDs in the rotary encoder can utilise for maximum brightness.

Initial draft schematic

For the circuit board, I had opted to use an Adafruit Perma-Proto board. This board is intended for use to “harden” a design that’s been prototyped on a push-fit prototyping board, but I was pretty confident in my design so I decided to go straight to soldering parts onto the Perma-Proto board. However, since the layout is very like that for a prototyping board, I used Fritzing to lay out the circuit - Fritzing is a CAD package that is specifically design for working with solders breadboards of this kind.

I did find that interoperability between Fritzing and just about anything else is not very good; for example, I had no way of importing the netlist of my KiCAD schematic into Fritzing so I had to manually check the connectivity of the circuit by eyeball. Here’s the initial layout in Fritzing.
Fritzing layout


The first thing to be assembled was the wooden enclosure. Using PVA white glue, I bonded the sleeve crenellations together and inserted the T-nut holders into the slots pre-cut into the sleeve. Once that was dry, the T-nuts were put in place and the front and back face screwed in place to pull the T-nut teeth into the back of the holders. When the glue had set, I put the DIN connectors in for the MIDI out and fitted some of the buttons and switches to see how it looked.

Next was soldering up the components on the circuit board according to the layout and then wiring up all the connectors to the board. This was a reasonably time consuming step since getting the wires the right length to allow the easy assembly and disassembly of the front and back panels to the sleeve.

Coming soon: Bringing up the design

Sunday, 10 April 2016

Big Clock: building a MIDI Master Clock, part 1

As part of a musical project I’m involved in, we have a few pieces of old school MIDI hardware (drum machines, arpeggiators etc.) that can be synchronised to a MIDI clock; this is a standard that distributes tempo information around a MIDI network to keep everything running in time. Although it’s straightforward to generate MIDI clock from a computer, we wanted to be able to potentially play out with no laptops involved in the setup, so I decided to investigate building a MIDI clock generator for our hardware rig.

Tuesday, 15 March 2016

Repairing an Axon AX 100 guitar-to-MIDI converter (part 2)

(Note: this was originally posted on the Edinburgh Hacklab blog on 4th April 2015)

(Return to Part 1)

So the replacement LCD (a Midas MC21605B6WK-FPTLW) arrived last week, and I headed to the lab to try it out.

Repairing an Axon AX 100 guitar-to-MIDI converter (part 1)

(Note: This post originally appeared on the Edinburgh Hacklab blog on the 24th March 2015)

I've wanted a Guitar-to-MIDI converter (a.k.a. a guitar synth) for yonks. In particular, I've been looking for an Axon AX 100 unit; they were renowned for the speed and accuracy of the tracking that the proprietary neural network software could achieve. Unfortunately the AX 100 has been out of production for years, and used units are commanding prices in the high hundreds of pounds. However, I recently found a reasonably priced spares-or-repair unit on eBay, so I picked it up.

Sunday, 13 March 2016

Post 0: Welcome, and an introduction

Hello there, and welcome to my new blog; let me introduce myself and what this blog will cover.
Photo credit - @tinyblob

I am a maker and hacker living in Edinburgh with a particular interest in music and audio, playing with everything from MIDI to synthesis to valve amplification and everything else in between. I was a co-founder of the Edinburgh Hacklab makerspace and most of the things you'll see here will be at least partly developed in there - indeed, I've blogged a few times over there already.

The blog was primarily born out of a desire to share some of the discoveries I've made with pieces of equipment I am working with, but I'll also try to show some of the things I'm working on as they are developed.

If you find anything useful or interesting, please get in touch to let me know!