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CIRCUIT
DESCRIPTION
The following circuit description begins with a discussion
of the instrument using the block diagram located in the
Diagrams section at the rear of this manual . Then each
circuit is described in detail , using detailed diagrams where
necessary to show the interconnections between the stages
in each major circuit and the relationship of the side -panel
controls to the individual stages . In addition to the block
diagram , complete schematics are given in the Diagrams
section .
Block Diagram
Signals to be displayed on the CRT are applied to the
tips of the signal probes . The signals are then amplified by
the appropriate channel Input Amplifier circuit , consisting
of a two-section source -follower stage and two feedback
amplifiers . The Input Amplifier circuits also contain the
vertical deflection , position (with channel on-OFF ), input
coupling , variable attenuation , and balance controls .
The Trigger Generator circuit initiates the sweep signal
produced by the Sweep Generator . The input signal to the
Trigger Generator can be selected internally either from the
capacitively coupled CH 2 Input Amplifier signal , or from
the directly coupled COMPosite signal of the Feedback
Amplifier. The Trigger Generator input signal can also be
selected from the external signal applied to the EXT TRIG
jack . The Trigger Generator circuit contains coupling and
source controls in addition to a combination level/slope
control .
The Sweep Generator circuit produces a linear sawtooth
output signal when initiated by the Trigger Generator
circuit. The slope of the sawtooth signal is controlled by
REV . B , AUG.1 976
Circuit Description - 212
the SEC/DIV switch . The Sweep Generator circuit also
produces an unblanking gate signal coincident with the
sawtooth waveform . This gate signal unblanks the CRT to
permit display presentation .
The output of U370 is amplified by the Horizontal
Amplifier
circuit
to
produce
the
correct horizontal
deflection for the CRT for all positions of the SEC/DIV
switch . The
Horizontal
Amplifier
contains
a variable
magnifier to increase the sweep rate up to at least a
maximum of five times in any position of the SEC/DIV
switch .
The Power Supply and CRT circuits provide all the
voltages necessary for operation of this instrument .
Circuit Operation
In the following description of the electrical operation
and relationship of the circuits in the 212 , circuitry
commonly used by TEKTRONIX is only briefly explained .
If more information is desired on the commonly used
circuits , refer to the following textbooks :
Phillip
Cutler ,
"Semiconductor
McGraw - Hill , New York , 1964 .
Circuit
Circuit
Analysis " ,
Lloyd P. Hunter ( Ed . ) , " Handbook of Semiconductor
Electronics ", second edition , McGraw - Hill , New York,
1962 .
Jacob Millman and Herbert Taub , " Pulse , Digital , and
Switching Waveforms " , McGraw - Hill , New York , 1965 .
6-1
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