Tag Archives: DIY electonics

sip2: amazing oscillators

by Larry Dunn, July 21, 2020

Create the Future! Building our own amazing oscillators was the objective for week 2 of Synth in Place, the online course in building DIY electronic music-making machines, taught by Kirk Pearson and presented by Dogbotic sounds labs and Thingamajigs. We took our inspiration for this challenge from a couple of truly awesome, and famous, installations, made by pioneers in the electronic museum field. One of these was composer and sound artist David Tudor‘s Rainforest V (variation 1), at the Museum of Modern Art in NYC, as shown in this 360° video.

Another inspiration came from Daphne Oram of the  BBC Radiophonic Workshop, which she founded in 1958. Her Oramics Machine is a visual synthesizer that uses drawn images to create sounds.

Of course, our first oscillators could not even scratch the surface of the genius of the work of these transformational thinkers and makers of electronic instruments. But we nonetheless are doing our work in homage to their path-setting work.

Oscillators are a foundational building block of electronic music synthesizers. For the uninitiated, an oscillator is an electronic gizmo that makes electrons move back and forth in a normal predicable manner. That predicable pattern can be exploited to activate other electronic components such as led-lights and speakers. With the proper setup of circuits and wiring to control the frequencies in the pattern of electron movement, what comes out of a speaker in such a setup can be pitched sounds in the range we typically call music.

Our first oscillator, a flashing LED (screen shot from Kirk Pearson demo video)

Using a breadboard (a temporary circuit board made for prototyping electronic gadgets); a 555 Timer (a ready-made microchip that can control electron pulses in a variety of ways, depending on how you connect it); a handful of capacitors, resistors, and wires; a bare-wire LED bulb; a potentiometer; a small speaker; and a 9-volt battery, with snap-on connector; we set out to create the future. Our first oscillators evolved through several versions. The first, show above, implements a simple strobe light. The frequency of flashing is controlled by your choice of capacitors. If we add a potentiometer (a sort of switch that can be used to vary the flow of electrons) and a speaker into our design and rewire things a bit, we suddenly have a user-controlled noise-making machine. And if we can get the frequencies in the right range, our noises will be pitched sounds we could call music. Below is a look at that setup.

Prototype sound-producing synthesizer (screen shot from Kirk Pearson demo video)

For the final trick, we ventured into Daphne Oram territory. Remove the potentiometer and do a bit of rewiring to connect a piece of corrugated cardboard filled with a heavy smear of pencil lead (graphite, i.e. carbon, i.e., a conductor of electrons) using an alligator clip in contact with the graphite smear, with a bare wire at the other end suitably connected to the breadboard. Use another wire of the same configuration, similarly connected, and you can “play” the graphite smear using a drawing gesture with the other alligator clip. Here is the way that setup looks.

Crude homage to Daphne Oram (screen shot from Kirk Pearson demo video)

I struggled to get my own version of these oscillator variations working properly. These components, especially breadboards, can be temperamental, to begin with. And whatever manual dexterity I once had (which was not that much) is fading fast with age. As arthritis and other woes take up residence in my hands, you can call me Klutzy McFumblefingers. But, despite the challenges to actually get these things working, learning how they go together to make newly-imagined instruments is a thoroughly engaging experience.

Stay tuned.