Design Device
   by Tom DeWitt, 1975 (part 17 of 18)

use by video artists. The Electronic Music Studio at SUNYA under the direction of composer Joel Chadabe has been a focal point for the development of new synthesis systems. Its test equipment includes a Tektronics 465 video oscilloscope, two bench waveform generators, a digital VOM, a high sensitivity analog VOM and several bench power supplies. It also houses the unique Moog CEMS audio synthesizer and an interfaced PDP 11/10 minicomputer with a user adaptable backplate. WMHT has an identical PDP 11/10. Additional test equipment available to the project includes a Hewlett Packard sampling oscilloscope which is used in debugging high speed digital circuits.

In an instrument like the Design Device many of the components are inexpensive integrated circuits which are commonly available from a variety of distributors including surplus houses. The greatest expense is putting the circuits together. This may involve tens of thousands of interconnecting wires. To simplify construction, the Design Device will use printed circuit technology to mass produce all redundant circuits. While saving enormously in labor, this technique will raise the hardware cost. This cost is seen most in the matrix switching system which forms the backbone of the synthesizer. It will be constructed of two large glass-epoxy printed circuits carrying 92 bus lines. The decoding and switching circuits will also be built on printed circuit boards which will then be mounted on generalized wire wrap boards. There will be twelve general purpose boards used in the device. Each one will have a hand constructed circuit on it containing one to three of the processing modules. All the active circuits will be mounted in a standard 19" rack, and manual controls will be brought out on an independent control board.

In budgeting labor for construction, a general rule of $6 per hour has been used, although the actual amount will range from $10 to $4 depending on the skills of the worker. As Tom DeWitt will be living on the stipend from NEA, his labor is donated. Additional savings will be realized in donated equipment from WMHT including two quality vidicon cameras, two black and white monitors, and access to the PDP 11/10. The Rutt display system to be used will be donated by Tom DeWitt at about half its market price.

In the event that the entire project is not funded, specific modules can be realized separately, but the hardware expenses worked into the matrix switch budget must be included, that is, circuit boards, power supplies and mounting gear. These would roughly double the cost of any one module as currently budgeted.