Specifications

Section 1. Installation and Maintenance
1-10
1.3.3.4 A100 Null Modem Adapter
The A100 Null Modem Adapter is used when 5 volts is needed to power
external modems with the PS100 or CH100. The A100 supplies 5 volts to pin
1 of the 9 pin null modem ports. A common use for the A100 is in
radiotelemetry networks.
The maximum current drain on the 5-volt supply of the A100 is 150 milliamps.
1.4 Solar Panels
Auxiliary photovoltaic power sources may be used to maintain charge on lead
acid batteries.
When selecting a solar panel, a rule-of-thumb is that on a stormy overcast day
the panel should provide enough charge to meet the system current drain
(assume 10% of average annual global radiation, kW/m
2
). Specific site
information, if available, could strongly influence the solar panel selection.
For example, local effects such as mountain shadows, fog from valley
inversion, snow, ice, leaves, birds, etc.
Guidelines are available from the Solarex Corporation for solar panel selection
called "DESIGN AIDS FOR SMALL PV POWER SYSTEMS". It provides a
method for calculating solar panel size based on general site location and
system power requirements. If you need help in determining your system
power requirements contact Campbell Scientific's Marketing Department.
Connect solar panel leads to the green connector at the side of the CR3000
next to the power switch (rechargeable base only). Polarity does not matter.
1.5 Direct Battery Connection to the CR3000 Wiring
Panel
Any clean, battery backed 11 to 16 VDC supply may be connected to the
Power In terminals on the front panel. When connecting external power to the
CR3000, first, remove the green power connector from the CR3000 front
panel. Insert the positive 12 V lead into the right-most terminal of the green
connector. Insert the ground lead in the left terminal. Double check polarity
before plugging the green connector into the panel.
Diode protection exists so that an external battery can be connected to the green
G and 12 V power input connector, without loading or charging the internal
batteries. The CR3000 will draw current from the source with the largest
voltage. When power is connected through the front panel, switch control on
the standard CR3000 power supplies is by-passed.