Electronics Design

Over the years I have designed and built various devices for interactive art installations, live music performances, interactive theatre and occasionally just for fun. Here are some of them.

Stereo electret phantom power interface

This device allows low cost electret capsules (that have an internal FET such as the Primo EM172) to be powered by 48V phantom power. The mic-level low-impedence audio output is fully buffered and balanced using a low noise circuit allowing for long XLR cable runs. Phantom power current consumption per capsule is 3.5 mA. The interface also features a 10 dB pad and an 80 Hz high pass filter.

A new version of this phantom power adapter for electret mics and capsules is now available from making-sound.co.uk.

Kramer VS-1616A Remote Control System

The design and build of a remote control panel system for a Kramer VS-1616A audio matrix.

Read more…

Analog sensor and expression pedal MIDI interface

Converts 8x analog sensors and/or expression pedals into any MIDI messages with basic mapping funcitonality (scaling, thresholds etc.). 6.35mm stereo jacks. Compatible with most expression pedals (Yamaha wiring: tip = +V, ring = wiper, screen = ground), and all 5V analog sensors. MIDI data received at the MIDI input is merged to the MIDI output. Programmable using Windows and Mac software via the MIDI in port.

Expression pedal meter

Sometimes it is important to know the exact position of an expression pedal when playing a keyboard (e.g. knowing the volume before playing a note). This device provides a visual indication of the expression pedal position. It is inserted between an expression pedal and a keyboard’s expression pedal input. A switch selects between Roland and Yamaha expression pedal wiring and a CAL control calibrates the meter.

Audio power amplifier

This 4-channel power amplifier was designed and manufactured to a precise specification for a large-scale art installation in Sydney. Each amplifier has one fully balanced input with ground lift that feeds four power amplifiers. Input sensitivity is adjustable. Fully protected 12V DC supply input.

More info on the art installation here

MINI-IO sensor interface

A sensor network development environment for art installations, interactive music and dance performances, immersive museum exhibits, theatre productions etc.

More info…

Motion capture suit

Motion capture suit graphic

A wireless motion capture suit with real-time vibrotactile feedback.

More info…

Electromagnet driver

Stackable four-channel electromagnet driver board

A device to drive electromagnets using audio signals. Translates analog audio signals into electromagnetic waves for resonating metallic objects including strings, bars and metal plates. The pitch, waveform and dynamic level of the audio signal is preserved allowing for a range of sounds and timbres.

Stacked driver boards, cabling and electromagnets

Boxed up prototype

Each board can drive four electromagnets. Boards can be stacked to accommodate more electromagnets. Power is shared between the boards requiring just one DC power adapter for all boards and electromagnets. Pluggable terminal blocks allow different electromagnets to be interchanged quickly. Each audio input has an LED that lights up when the input signal reaches -3dB before clipping. The voltage and maximum current can be adjusted to suit a range of electromagnets.

As used in the electromagnetic harp project.

Audio-rate sensor interface

This devices transforms your audio interface into a high-resolution, high-speed analog sensor interface.

The device modulates sensor signals into the audio frequency range that allows the use of an audio interface to capture the modulated sensor signals that can then be demodulated in software. Using an audio interface as the input device to the computer allows for very high resolution, high data rate and low latency. This is particularly useful for time critical applications where any latency or resolution artifacts are not acceptable. Such uses includes the design of electronic instruments and controllers that must be sensitive to very subtle nuances of performer movements.

The audio-rate sensor interface was designed for live performances and needed to withstand the rough treatment that it would inevitably receive. It is housed in an aluminium enclosure and uses 6.35mm jacks for sensor inputs and audio outputs.

Used by Richard Baker for his piece “Tyranny of Fun” (sound design by Nye Parry).

More info…

Remote sensor interface

Designed to provide a quick means of connecting several sensors in a remote location to a computer in order to control audio/video/lighting software for art installations, theatre and interactive museum exhibits.

More info…

LED analyser

A simple device to compare several LEDs simultaneously at different forward currents, with a forward voltage read out. More info…

Custom MIDI controller

A general purpose programmable MIDI controller with 10 program change buttons, 2 toggle switches and 4 expression pedal inputs. Ideal for when only a few buttons and/or expression pedal inputs are needed. Has a 5-pin DIN MIDI output so is easily split to a back-up system. MIDI input is merged with controller data. Built using a Kenton AN16 analogue input to MIDI module board.

Contact speakers

A system to turn surfaces into speakers. Each element can be glued to a surface, hidden from view, causing it to behave like a speaker cone and emit sound. Multiple elements can be attached to the same surface to distribute sound over a wide area. The black box takes one audio input and has four individually amplified outputs for the elements. I have called them ‘contact speakers’ because they work very much like a contact microphone, only in reverse. Surfaces that work well include cardboard boxes, poster board, polystyrene, plastic lids, drum skins or any surface that is not too dense. They produce almost no sound when not attached to anything, but as soon as they come into contact with a surface they produce a surprisingly high volume if the surface allows for it.

DIY omnidirectional microphones

How to wire up a pair of very low cost electret microphone transducers for stereo and binaural recording.

More info…

MIDI motors

USB Motor Interface (back)

Control up to 4 DC motors individually using MIDI continuous controller messages. Up to 12V/4A (13A peak) per motor.

Ultrasonic sensor interface

Connect up to 18 ultrasonic sensors to this interface with standard Ethernet cables. The sensors are properly synchronised so that the ultrasonic bursts from different sensors do not interfere with each other. The interface contains a web server and has an Ethernet connection to the computer.

More info…

Lift interface

A device to translate control signals from a lift to MIDI data that triggers samples depending on which buttons are being pressed in the lift, and the position of the lift.