Creative Solar Power Archive

How it Works: Direct Drive Circuits

Characteristics of a direct drive circuit: 1) works in direct sun 2) stops when a bird or cloud passes over 3) doesn’t work at night

The simplest circuit you can make with a photovoltaic cell is a direct drive circuit; just some cells in series with a load.

A basic direct drive motor circuit, used in Joe Jones’ instruments and Alex Nathanson’s Type 2 Kinetic Sculptures

At its most basic level there is a 1 to 1 connection between the power the photovoltaic cell is generating and the output of the circuit. While the circuit is simple, with a little creativity you can make a wide range of dynamic projects with these basic ingredients. This simple circuit can be applied to different media types and without changing the electrical components, you can change the behaviour of the project by considering the physical placement of the materials.

Put simply, when the light goes away the load stops working and when the light is stronger the load is more intense; the light is brighter, the motor is faster, the sound is louder, etc.

A basic direct drive motor circuit, used in Joe Jones’ instruments and Alex Nathanson’s Kinetic Sculptures.

Joe Jones: Solar Music Hot House

Joe Jones (1934 - 1993) is a Fluxus artist whose instruments rely on elements of chance to create interesting musical compositions. Most of his solar powered instrument were direct drive wired DC motors with wire or other objects attached to the end of the motor shaft, which were placed in the vicinity of a stringed or percussion instruments. When a sufficient amount of sunlight hits the solar cell, the motor spins striking the objects near it.

Jones’ first solar powered instruments were built in 1977, but he began conceiving of them in 1964. In a 1975 illustration titled OUT-DOOR PIECE he describes how the work should function.

Many zitar, wind chimes, and drums, etc. are hung from trees at random distances at different positions from the sun so that at a certain time of day one or more will be playing as long as the sun shines becoming a sound forest.

There are four elements that determine how Jones’ instrument would sound. 1) solar cell choice 2) motor choice 3) percussive elements 4) physical position

1) The type, amount, and configuration of solar cells determines that power they produce. More or larger cells require less sunlight to turn the motor, while smaller cells may only work in the brightest light around noon.
2) The motor choice impacts the speed
3)The percussive elements determine the sound. Is the motor spinning a wire, a wooden dowel, a rubber ball, etc.? What is the motor striking? A stringed instrument like a zitar or a percussive instrument like chimes?
4) The physical position of all of these elements is the final determining factor in how these instruments function. How much sunlight does the location receive? Is it stationary or does it sway in the wind? Is it in a place where people might interact with it or is it out of reach?

Alex Nathanson: Kinetic Motion Studies

1) type 1: PV vibration bot 2) type 2: dc motor mounted PV 3) type 2: dc motor mounted PV