Appendix F. Excerpts From The 8032 Multiplexer Manual; Theory Of Operation - Geokon 8600-2 Instruction Manual

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APPENDIX F. EXCERPTS FROM THE 8032 MULTIPLEXER MANUAL

The following Appendix includes excerpts from the Model 8032 Multiplexer manual that apply
to the Micro-6000. A complete version of the Model 8032 Multiplexer Manual can be found at
WWW.GEOKON.COM.
F.1 Theory of Operation
The Model 8032 Multiplexer expands the number of channels that can be read by the MICRO-
6000 Datalogger. Channel switching is accomplished by mechanical relays mounted on the
underside of the circuit board and the transducer connections are accomplished by friction
locking spring-loaded terminals mounted on the top side of the circuit board.
To protect against lightning or EMI/RFI induced transients, each channel is protected by an
integrated lightning protection system, incorporating 230V tripolar plasma surge arrestors, 150V
bipolar plasma surge arrestors, 10uH inductors and 16V transient voltage protection diodes. See
Appendix A for complete specifications on these components.
The multiplexer is powered by a nominal 12 VDC supply. Two control lines (RESET and
CLOCK) determine how channel selection is accomplished. Two schemes are supported - one
when connected to the GK-403 Vibrating Wire Readout Box and the other when connected to
Micro-6000 Datalogger.
Two switching configurations are supported, 16-channels of four conductors (Figure 27) or 32-
channels of two conductors (Figure 28). The 16-channel, four wire switching configuration is
typically used to multiplex four wire sensors such as resistance strain gauge load cells. It is also
used to switch connections for instruments which have more than one sensor integral to them,
such as vibrating wire pressure transducers with an integral thermistor for measuring
temperature. The 32-channel two wire switching configuration is typically used to multiplex two
wire sensors such as a vibrating wire pressure transducers, thermistors or thermocouples.