Tektronix 3B5, Instruction Manual

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Circuit Description — Type 3B5
shunt diodes in the Readout Logic circuit. (The X100 mag­
nifier logic level may be zero volts for X100 magnification
in some positions of the MANUAL TIME/DIV switch.)
TABLE 3-1
Magnifier and Bar Magnifier
Logic Output Levels
Magnification
Ratio (switch
position or
external pro-
gram logic)
Logic output Level on Logic Lines
X1 X10 X100 X100
X1 (OFF) — 7 V 0 V 0 V 0V — 7V
X10 0 V
-12 V
0 V
-12 V -12V
X100 0 V 0V
-12 V 4
-12 V 0V
^Normally —12 volts. May vary between zero and —12 volts since
there is no “pull-down” resistor on the Xi00 magnifier logic line.
Readout Board
The Readout Board circuit shown on diagram 10 shows
the connection to this board and the bulbs which produce
the readout-panel display. The function of the bulbs and
the operating circuitry is described in the Sweep Generator,
Delay and Timing Circuit and the Readout Logic discussions
Voltage Distribution
Diagram 11 shows the distribution of the voltage from
the indicator oscilloscope through connector P21 to the
boards and connectors in this instrument. The decoupling
networks which provide decoupled operating voltages are
shown in this diagram and are not repeated on the indi ­
vidual circuit diagrams.
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