For my next step into DIY electronics, I’ve made a simple synthesiser using a few components connected together on a piece of technology called a breadboard. A breadboard is a very simple piece of kit, which consists of a number of contact points connected together by metal strips. Below is an example of the breadboard I have been working with:
As you can see, there are two lines of contact points at both the top and bottom of the breadboard. These are connected by horizontal strips of metal. The contact points in the middle of the breadboard are connected by vertical strips of metal, with a break in the middle to separate the two halves of the board.
This circuit was very easy to build, and is borrowed from the 2005 book ‘Handmade Electronic Music’, by Nicolas Collins. All it consists of is an Integrated Circuit (IC), a resistor, a capacitor, a few jumper cables, a 9 volt battery and an audio cable to connect it to an interface (via a couple of crocodile clips). Here’s the finished circuit:
In the circuit what you can see is that the positive and negative (ground) terminals of the battery are connected to the top and bottom rows of the breadboard respectively. The positive terminal is then connected to pin 14 (top left) of the IC via a jumper lead, and the ground is connected to pin 7 (bottom right). The resistor is connected to pins 1 and 2 of the IC, whilst the capacitor is connected to pin 1 of the IC and the ground of the circuit. A jumped cable connected to the ground is then connected to a crocodile clip, which in turn is then connected to the audio cable. Another jumper cable is also connected to pin 2 of the IC, which then is also connected to the audio cable via a crocodile clip.
Whilst all of the physical information about the synthesiser can be engaging, what I find most interesting about it is how it sounds! The circuit will usually just make a basic square wave, however I’ve added a light-dependent resistor into the circuit so that the pitch of the wave can be altered. It alters the pitch by varying the resistance depending on how much light gets in – the more light comes through, the less resistance is put into the circuit, which allows a larger amount of electrical current to flow through. More light therefore = higher pitch, and vice versa. This means the instrument can be played in a similar way to a theremin. This is how it sounds in its most basic form:
And here’s a video of me playing the synth like a theremin (the high pitched noise is someone else’s synth in the background, mine is the much lower pitched sound):
I decided I wanted to take this setup home for the week so I could record it and mess around with a few effects in my DAW. Here’s the same sound you just heard but with a few effects (autofilter, ring modulation, pitch shift, distortion, and a couple of others) to make it sound like a strange room of tweeting birds with a chainsaw in the background:
Here’s the same settings but with the autofilter turned off – this gives a very horrifying distorted sound:
Eventually I’d love to be able to make these effects as analog circuits in their own right!
For all of the previous recordings I was using a phone torch to illuminate the light dependent resistor as I felt the pitch was too low otherwise, so I decided to change things up a bit – in this next recording I switched out the 4.7μf capcitor which I had been using for a 0.1μf capacitor. This affects the range of the pitch that the light-dependent resistor will sweep through, and in this case as it is a smaller capacitor, makes the signal higher-pitched. Coupled with a rotary speaker emulation, this can give quite a nice ‘robotic bleep’ sound:
I also experimented with a touch sensitive resistor, which applies different amounts of resistance of the circuit depending on how hard you squeeze it. It was fun to experiment with, however I found it a bit less expressive than the light-dependent resistor:
Whilst on a break from making crazy sounds, I took a trip downstairs to the charity shop from the studio I was working in. I found a couple of children’s toys that I thought could be potentially candidates as housing for my final piece for this element. I know it’s quite a long way off still, but these toys inspired me quite a bit and I think I may have a couple of ideas for what I may want to exhibit in the second element of the unit as a whole.
Where is art without a sense of humour and play, after all? And wouldn’t it be amazing to enter a devilish room of these two and their friends screaming at you?
Bibliography
- Collins, N. (2006) Handmade electronic music: The Art of Hardware Hacking. New York, New York: Taylor & Francis Group.