I found this the other day – it’s not the recording circuit we used but a nice explanation, might be good for some ideas for the booklet/write up we’re handing out at ECA? It’s from Forrest Mims’ Mini-Engineer’s Notebook: Science Projects (1990) –
From our session on 20th March –
– Film/sound documentation from this setup session, rendered and onto blog (Raz).
– Mic clips to attach to bowls, another fan to order (Jim).
– Clips to be attached to bowls (Martha/Fiona).
– Poster and booklet for our showing (Raz).
– Facebook event (MC)
– Check our budget… re beer? 🙂 (Ian)
– Lamps to light space, black gaffer tape for next time!
The group met with Sean on 7th March to demo our fan unit into Max/MSP and discuss how things were going.
Sean suggested that our current plan, to manipulate the output of the fan units with Arduino and Max/MSP control, was perhaps too simplistic as a final piece, and we should think about adopting a more experimental approach to the final installation. He suggested a few things, including:
- The use of Martha’s kaleidoscope unit.
- More analog input from LDR circuits, including offering visitors the opportunity to ‘scan’ light sources in the exhibition space while walking around to add audio to the mix.
- A ‘soundbed’ of LDR-sourced sounds to be playing so that the installation is not silent at any point, with the possibility of ducking this audio once the fans start up, or cross-modulating between sources.
The group then discussed some options for inclusion in the final piece, including the idea of scanning a computer screen with black&white images on it to produce audio/data through an LDR. Some tasks were assigned for investigation before the next meeting –
- Raz will further develop the Max/MSP patch for filtering fan audio, and look at producing a video from the Arduino data collected.
- Ian will investigate data collection from a solar cell, to either produce an audio file or some data to affect the patch (correct me if I’m wrong here!).
Andreas and I met up this afternoon and did some experimenting with our builds to try to answer some questions raised. Here’s what we found:
- The RGB recorder circuit works fine with a AA battery and this reduces the level of output a fair bit, as well as thinning out the sound so there is less bass frequencies. It’s more textured, and might be more interesting to record with. When I remember tomorrow to bring in the AA battery holder Jim donated (silly me) I’ll attach it, so we have a choice of battery power when recording.
- We set up the fan unit and tried to get it moving with an LED torch, the LED attached to it, and a phone. It was really difficult as none of the light sources seemed to be strong enough. If these are going to be the interactive part of the installation (i.e. where people put their light sources) we need to look at providing light sources of a particular strength or investigating smaller fans, as it doesn’t look like they will react right away to light.
- I tried a quick opto-coupler to see if we could transmit the audio through an LED to point at another photoresistor. We got the LED lit (whoop) but the resulting audio was nothing like the input. I have a feeling my ground is in the wrong place or we’re missing a component. Will have a look at this tonight and hopefully we can try it out in the morning.
After our discussion yesterday re investigating colour filters to add complexity to our source recordings, I worked up a new (and even more triffid-like) version of the original circuit. It’s three lots of our photoresistor and 10K resistor, each going through its own capacitor to its own jack socket. They’re all powered by one battery, as there isn’t really any current drawn by the components as such. The voltage that flows through is just being measured as audio. So we could potentially power a lot of these off one battery I think, or at least one 9V source.
I packaged it up in cardboard so it’s easy to handle for now…
The filters for the photoresistors were made by rolling up acetate (spraypainted black), and taping a small piece of color filter on the end. These pull on or off easily.
I recorded (not in 3 channel yet as the recorder was booked out) some samples inside G11 in the dark with my LED torch, and outside around Nicholson Square at 9.30pm. Initial findings:
- No change in level from running 3 circuits off one battery.
- Something exciting happens with a red filter and an LED source indoors (intermittent high pitches).
- Black tubes give exceptional separation, to the point where the channel is totally silent if the tube is not pointed at the light source.
- Not clear just yet whether different sources were accentuated by the colour filters, but I was only monitoring while recording.