Things I've made

Here is a little list of things I've made and happened to take pictures of.

Cooling Attachment

At work we are building an instrument that generate a lot of heat in certain components. These components need to be cooled down in order not to overheat, so they are mounted on a heat sink. I made this attachent that clips onto the heat sink to keep it cool. Its performance is satsifactory.

Two fans mounted on a plate.

Picture Frame

When I left the Institute of Mathematical and Physical Sciences at the University of Wales Aberystwyth I received a watercolour of the Aberystwyth Marina as a going-away present. I framed it in a frame of my own design, made out of left-over wood from my dinghy.

The drawing of the frame was created in CorelDRAW 8 and exported to the DXF format. My father took the DXF file and machined the parts from 6mm marine ply. The jigsaw-like joint does not extend through the thickness of the material, and those joints were glued together. The wood was coated with two layers of Ultracote 520 polyurethane primer from NUI. Small stainless-steel plates are glued to the back, through which a thin stainless steel cable is threaded from which the picture hangs. The mounted picture is held in place by eight flexipoints.

A custom-made frame for a picture of Aberystwyth Marina

VHF Antenna

When SuitSat-1 was launched, I had unexpected free time. I quickly put together a quarter-wave ground plane antenna, from the instructions found at www.hearsat.org, and connected it to my AOR-8000 receiver. Unfortunately the power from the transmitter was much weaker than planned, so I could not hear anything. Fortunately, people with good antenna systems could record some transmissions and share it on the Internet.

A length of 32mm plastic water pipe carries a mild steel bracket. The chassis-mount BNC connector that carries the ground-plane radials and active element was salvaged from an amplifier of unknown vintage. The RG-58 feed line runs down the mast, under the overhang of the roof, along the beam and through the ceiling of my bedroom to my desk.

A quater-wave ground plane antenna fitted to a gable

Audio amplifier

This project had it's origins in the old days of telecommunications. We had a fax macine in kitchen, which also acted as the home phone (as opposed to the business phone). During winter months, when the doors were closed we could not hear the phone ringing. This was the design gap.

We did not want to break anything, or open the (expensive) fax machine. With some experimentation we found we could pick up the magnetic signal from the ringer speaker (it was a proper speaker and not a piezo thingy) and amplify it with an audio amplifier. So I designed this amplifier, which drove a speaker in the lounge.

To keep the whole system as tidy as possible I designed the amplifer to be tucked away in the corner of the telephone shelf we kept (and still keep) the fax machine on.

An audio amplifier tucked away in a very specific place

Inside the amplifier is quite simple, although I evidently didn't know much about electronics at the time. The amplifier is concealed in a shielded steel box, connected to earth. The power supply, however, was salvaged from a wall wart, and there is no regulation on it. It is simply a full-wave rectifier with a small capacitor for a little smoothing. No wonder the thing always had a hum on it!

The inside of an audio amplifier

Morse code beeper

This Morse buzzer I built to practice Morse code in preparation for a Voortrekker camp. I used a plan from Adventures with Electronics, using an astable multivibrator to generate the frequency. I must have built this on breadboard a year a two before I needed the Morse practice buzzer.

A simple morse beeper

To build it into the box I used a printed circuit from an IBM computer (via my dad) from which I removed all the components. The components were also harvested from IBM computer boards: it took lots of time hunting to find the right ones! The big cylindrical things in the picture are paper capacitors. The Morse key is simply a little strip of mild steel sheet, that touches a screw for a contact. Crude, I know, but I was probably about 15 years old at the time.

The transistors are IBM transistors, NPN, probably, desoldered from similar boards. I identified them by their part numbers. The speaker was probably salvaged from a transistor radio that died.

The inside of a simple Morse Code beeper