Agilent 34970A/34972A Data Acquisition / Switch Unit

Chapter 5 Theory of Operation
Switch Modules
A single relay is used to switch two input channels. The choice of which
channel is connected to the common is performed by relay K422.
Channels are paired 20 channels apart (Ch 1 with Ch 21, Ch 2 with Ch
22, etc.) Relay K421 connects the common to the backplane analog bus
for use with the internal DMM.
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