Vertical Amplifiers
Trigger
and Horizontal
Amplifiers
2212 Service Manual
Block Diagram
This subsection contains a description of the simplified 2212 blockdiagram
(Figure 3-1).
In the 2212 oscilloscope the following main parts can be distinguished:
Vertical Amplifiers
- Trigger
and
Horizontal Amplifiers
- Digital Storage
Front panel and System Control
High and Low Voltage Power Supply
Z-axis
The
vertical amplifier has two
input
channels. They consist of a programmable
attenuator, a FET input buffer and a pre-amplifier circuit.
The pre-amplifier contains a digitally controlled gain switching circuit and a
vertical enable input. The overall gain of the pre-amplifier can be controlled
with a de voltage. The output signals
of
pre-amplifiers of
CH1
and
CH2
are
differential signal currents, that are summed
in
the
input
stage
of
the
delay line
driver. The pre-amplifier provides also a trigger signal and a vertical signal for
the digital storage circuit. Attenuation, gain and mode of the pre-amplifier
circuits are controlled by the system control circuit. Control data is loaded
in
a
shift register chain and applied to the appropriate inputs of the pre-amplifiers.
The
vertical positioning signals and vertical readout data are through the verti-
cal position control circuit applied to the delay line driver. The delay line driver
amplifies the signal to a level sufficient to drive the vertical output amplifier.
The
trigger circuit receives
input
signals from the
CH1
and
CH2
pre-amplifiers,
from the
EXT
trigger
input
and from a line source.
Source selection is performed with digital control signals. The
output
signal
from the trigger circuit is connected to thesweep logic and sweep generator
circuit.
The
sweep logic determines the mode of operation of the sweep generator. The
mode of operation and the sweep speed are controlled by the system processor.
The
sweep logic also generates hold off signals to allow the sweep generator and
horizontal amplifier circuits to stabilize after sweep return.
3-3
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