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| An Annoyance of Solar Jerks |
| EMAIL TO ORDER: mroztronium@gmail.com Solar Jerk DIY PCBs (4-Pack) $100 shipped in the US Contact me for international shipping quotes, bulk discounts and workshop inquiries A step-by-step build guide for beginners is available here |
Solar Jerk is concerned with portability and autonomy. Site specificity can be deeply considered, casually engaged with or shrugged off. It is directly solar-powered and no battery is required. It is most active outdoors in direct sunlight, but can also howl away in a windowsill. PCBs are available to order in a pack of 4. You'll want more than one PCB. Let me explain...
The front of the board shows the parts you'll need and where to place them, as well as the components that can be adjusted to change parameters.
The back of the board is where you solder. It has a table to help you decode the roles of the adjustable components and hints at some ranges of component values to experiment with. Choosing the values of these special components is the way you tune the circuits and customize them to your liking. Here are some interpretations of their roles:
CB: Capacitor Bucket
- An oasis in the desert. The larger the capacitor, the greater the capacity of the reservoir. Solar Jerk is more excitable and erratic when thirsty though is more stable when its thirst is quenched. The more assertive it gets, the more it consumes. Consider this balance.
CT1 & CT2: Timing Capacitor
- Simple stuff. Each adjusts the rate of an oscillator. Bigger cap equals slower oscillator. Audio rate and glacial sub-audio rate are both viable.
RT1 & RT2: Timing Resistors
- One for each oscillator again. Works in tandem with the Timing Capacitors to set frequency range of each oscillator. Bigger resistor equals slower oscillator.
RV 1 & RV 2: Division
- These resistors create a ratio in the form of a voltage divider that adjusts how much one of the oscillators affects the core Jerk circuit. RV1 is the top of the divider and RV2 is the bottom. More division means more curiosity and openness. Less division means more authority.
CJ1, CJ2, CJ3: Jerk Capacitors
- These capacitors tune the behavior of the Jerk circuit and affect its overall timbral qualities. They don't have to be the same values. Experimenting with values will reveal their function.
RG: Jerk Gain
- Sets the gain of the first integrator. Highly interactive with all other component choices. Larger resistor equals more gain. Ride the fader like David Tudor or gun it Borbetomagus-style.
RFB: Jerk Feedback Loop
- Sets how much feedback there is between the input and output of the Jerk. Also highly interactive with all other component choices. If the Jerk were a filter, this could be thought of as a component that affects "resonance", however the Jerk is not a filter. Larger resistor equals less feedback.
You can also turn the Solar Jerk into an instrument with an interface by wiring up potentiometers in lieu of resistors or switches to select different component values, but keep in mind that as you add control you sacrifice autonomy.
There is also an "Indoors Mode" that allows you to use a 12V DC wallwart to power the circuit in lieu of a solar panel. This is offered as a concession for nocturnal living and vampires. If you're using a solar panel, don't stuff the components in the Indoors section!
The inspiration for working with sun and shade as changing parameters for electronic music goes back to electro-mechanical experiments in the late 1970's by Fluxus artist Joe Jones and an oscillator sound installation by Alvin Lucier called Solar Sounder. There are now dozens of practitioners worldwide working with notions of solar-powered electronic music and kinetic art. Check out the wonderful Solar Power for Artists website [1] for historical and contemporary examples.
Solar Jerk is based on concepts from JC Sprott's New Chaotic Jerk circuit [2]. In tinkering with this circuit on a breadboard and adapting it for single supply operation and solar power [3] I discovered that it has a tremendous variety of behaviors depending on the component values you choose. There is no "best sounding" variation. Each Solar Jerk has its own personality and routine that it performs in response to sunlight.
I also found a trick for enticing the circuit to morph between chaotic and periodic states by driving what would normally be a virtual ground connection with a triangle wave oscillator. A second triangle wave oscillator also drives the first integrator.
So the interplay between sunlight, the two oscillators and the component selection leads to some astonishing complexity for a relatively low-parts count circuit. When building an Annoyance of Solar Jerks you can pursue diversity in the variable component choices between each build in order to produce distinct voices [4] or strive for homogeneous builds in which micro-variations are determined more by light levels and sensitivity to initial conditions.
Don't be scared to experiment! Showing a little extra leg when stuffing components makes it easier to substitute the variable components or experiment with parallel and series combinations.
PARTS LIST (available via Tayda, Mouser and eBay)
OUTDOORS ONLY:
(1) 9V 3W Solar Panel (eBay)
INDOORS ONLY:
(1) 1N4001 Diode
(1) 10uF Electrolytic Capacitor - at least 16V rating
(2) 0.1uF Poly Film or Ceramic Capacitor
(1) 7809 Voltage Regulator
(1) DC Jack
VARIABLE COMPONENTS:
(1) CB: None - 1000uF Electrolytic Capacitor - at least 16V rating
(2) CT1-CT2: 0.1uF-220uF Poly Film or Electrolytic Capacitors - at least 16V rating
(2) RT1-RT2: 47k-2.2M Resistors
(2) RV1-RV2: 47K-220K Resistors
(3) CJ1-CJ3: 102-224 (0.01uF - 0.22uF) Poly Film Capacitors
(1) RG: Link-100K Resistor
(1) RFB: Link-100K Resistor
EVERYTHING ELSE:
(1) Speaker or Surface Transducer: 8ohm and at least 1W
(1) 470 ohm Resistor
(11) 10K Resistor
(4) 47K Resistor
(1) 470K Resistor
(1) 0.01uF Poly Film Capacitor
(1) 1uF Poly Film Capacitor
(1) 10uF Electrolytic - at least 16V
(1) LED - Red tends to works well, feel free to experiment
(1) NJM2073 Power Amplifier IC (eBay)
(2) TL074 Quad Opamp
(1) 8 Pin IC Socket - optional
(2) 14 Pin IC Socket - optional
Rules of Enjoyment:
Beware the orientation of polarized components (Everything except resistors and poly film capacitors)
Make sure the parts you order are Through Hole not Surface Mount
Send me documentation of your Solar Jerks in action
Sources:
[1] http://www.solarpowerforartists.com/archive/index.html
[2] http://thor.physics.wisc.edu/pubs/paper352.pdf
[3] https://www.youtube.com/watch?v=5UkdFkFgrHk
[4] https://www.instagram.com/p/CFDEaZtBEJw/
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