Negative tracings prodn. for printed circuits - using conductive plate laid over light box and traced using electric pencil

摘要

The machine produces a negative tracing for printed circuit work or microfilming. It comprises a box (6) with a sloping translucent surface (4), with a light source inside. Around the edges of this surface are electrically conductive strips (7) and a conductive plate (3) is laid over these. The plate has a translucent base and a chemically conductive surface. A pen (13) with a metal point (14) is connected by a cable (11) to an electrical supply (9). This is rheostat controlled (8) and the pen is used to draw the design on the plate. The passage of current reacts with the chemical layer to produce a mark.