Tabor 8020, User Manual

Page: 71 / 111

of U34. The reference for the DAC is provided from the
output of the reference source.
UP/DOWN CURRENT SOURCES - The output from
the DAC from U34 is voltage shifted by Q10 and applied
to a voltage mirror U27 and Q9. The emitter of Q9 drives
the up current source while the collector, through CR8
drives the down current source. The up current source is
formed by U25, Q6 and their associated components. The
down current source is formed by U26, Q7 and their asso-
ciated components.
TRIGGER CURRENT SOURCE - The same precision-
current generator, which supplies the down current
source, supplies the current to the trigger current source.
The trigger current source is doubled and compared with
Figure 6-1. Model 8020 - Symplified Block Diagram
Theory Of Operation Model 8020
Page 6-2