Horizontal Drift Variable Clock
Name of tool: Horizontal Drift Variable Clock
Inventor/Designer: George Brown and the Vasulka
Date of design: 1972
Description of the tool
The Horizontal Drift Variable Clock is not in itself an instrument, but rather an external source of synchronization that can control the horizontal displacement of a video image. By adding an oscillator with the capacity to go up to 15,000 cycles to the portable camera adaptor (Sony Portapak), it is possible to control the voltage of the horizontal synchronization signal. Typically, two cameras make up the system: one camera is hooked up to the normal vertical and horizontal synchronization signal, while the other camera, whose image is being superimposed or keyed on the first, receives a different horizontal frequence. This will then result in the horizontal movement of the image towards the right or the left. The Vasulkas also used this technique to cause images to travel from one monitor to another in multi-monitor compositions.