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CHAPTER 7·
THE TRACK-STORE,
D/A
SWITCH TRAY
7.1
INTRODUCTION
The Model 0.42.0341 Potentiometer, Track-Store,
D/A
Tray (Figure 7.1) has
patching terminations for three different types of circuits.
These include
patching for five attenuators (-5 through -9), one track-store
(TIS)
unit and
two
D/A
switches.
A description of the attenuator operation is included in
Chapter 3 of this manual, and is not discussed in this chapter.
The remaining
circuits
(TIS
and
D/A)
are described in the following paragraphs.
7.2
THE
TRACK-STORE CIRCUIT
The track-store
(TIS)
circuit (Figure 7.2) consists of storage capacitors, three
electronic switches (track, long store, and short store), an IC'network, and a
control circuitry.
Figure 7.3 gives typical
TIs
patching.
The resistor junction
(RJ)
of an ampli-
fier is patched to terminal TJ.
The switch junction (SWJ) terminal and terminal
TF are patched to amplifier terminals
AJ
and 0 respectively.
Terminal T (track)
is patched to a logic signal which controls the mode of the unit.
The lower IC
terminal (track IC input on Figure 7.2) is patched to a logic signal which places
the unit in the IC mode.
It overrides the T logic control signal.
The upper IC
terminal provides an input for the analog initial condition voltage for the store
capacitors.
When the track (T) input is high, the track electronic switch is closed connecting
the TJ terminal with SWJ, and the store electronic switches are open.
A low at
the T terminal causes the track switch to open and the store switch to close.
Consequently, the unit is in the track mode when the T input is high and in the
store mode when the T input goes low.
A high at the (track) IC terminal energizes a relay which connects the TJ ter-
minal to the
D/lO
selector switch on the main contro'l panel, permitting
a
de-
rivative readout.
A second set of relay contacts permits charging the store
capacitors to the IC analog voltage through the IC terminal.
7.3
THE
D/A
SWITCH
The
D/A
switch and its control input are terminated at the SW, 10, and SWJ
patching terminals (Figure 704).
The SW terminal provides a control input.
A logic signal at this point turns the switch on or off depending on its volt-
age level.
A high (+Sv) causes the switch to conduct while a low (0 volt)
holds the switch in a non-conducting state.
The 10 terminal is lOX (10K) times input of the switchw
Any analog input to be
switched is patched at this terminal.
7-1
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