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Decoder (detail) Cart
Tool Identification

Name of tool: Decoder
Creation date: 1966
Designers: Billy Klüver, Cecil Coker, Robby Robinson, Herb Schneider
Dimensions: 6” x 6” x 10”

Historical Notice

A simplified version of the decoder was developed for John Cage’s Variations V in 1965 by Billy Klüver and Cecil Coker. The same principle was used for 9 Evenings. Robby Robinson and Herb Schneider refined the decoder, notably by introducing the possibility of triggering a series of events rather than a single event only. This instrument, both alone and as part of a series, was one of the key components of TEEM. It was used in virtually every performance. For example, in Vehicle by Lucinda Childs, it allowed for the random triggering of lights, while in Solo by Debora Hay, it was used to control the carts.

Tool Description

Recognition of an audio signal frequency and triggering of a relay according to the presence or absence of pre-defined tones.

Summary of Materials

Box, battery and electronic components


Thirty-six transistors, five Reed relays, five relays, 15 switches, five small indicator lights.

Operating Procedure

An audio frequency was recognized by one of the five reeds adjusted to a specific frequency, which in turn triggered one of the five corresponding relays. The relays were connected to various electronic and/or mechanical artefacts. The connected component “played” while the tone sounded. Switches reversed the polarity, allowing the relay to be activated when no tone was present. The positioning of the two transistors provided the device with a short-term memory or a pulse generator. This principle allowed all five relays to be controlled in cascading order at defined intervals: a tone triggered a relay, its associated transistors triggered a second relay, and so on. It was possible to link many decoders together and in doing so increase the commands in a cascading fashion. It was also possible to trigger the decoder directly using a switch, without requiring an audio input.


Control of electronic and mechanical artefacts; command sequencing; creation of loops; randomness.

Documents Consulted

Herb Schneider, A glimpse or more at some technical aspects not seen by the third partner of Nine Evenings – the public. Experiments in Art and Technology. Records, 1966-1993, Research Library, The Getty Research Institute, Los Angeles, California (940003).

Billy Klüver, “Interface: Artists/Engineers,” E.A.T. Proceedings, no. 1 (Apr. 21, 1967) p.1-23.

Herb Schneider: A View from Central. Experiments in Art and Technology. Records, 1966-1993, Getty Research Institute, Research Library, Accession no. 940003. Box 2, file 16-17.

Vincent Bonin © 2006 FDL