SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS
3-8
3.4.3.2 PS12LA Lead Acid Power Supply
The PS12LA power supply includes a 12V, 7.0
amp-hour lead acid battery, AC transformer,
and a temperature-compensated charging
circuit with a charge indicating diode. An AC
transformer or solar panel should always be
connected to the PS12. The charging source
trickle charges the lead acid batteries which
power the datalogger. The internal lead acid
battery continues to power the datalogger if the
charging source is interrupted. The PS12LA
specifications are given in Table 3-8.
The two leads from the charging source can be
inserted into either of the CHG ports on the
PS12LA wiring strip; polarity doesn’t matter. A
tranzorb provides transient protection to the
charging circuit. A sustained input voltage in
excess of 40V will cause the tranzorb to limit
voltage.
Some solar panels are supplied with a
connector. This connector must be clipped off
so the two wires can be inserted into the two
terminal ports.
The red charge light is on when AC power or a
solar panel is connected to the PS12. If the
input voltage is high enough, the battery will
charge even when the datalogger is on.
CAUTION: Switch the power to OFF
before disconnecting or connecting the
power leads to the Wiring Panel. The
Wiring Panel and PS12LA are at power
ground. If 12V is shorted to either of these,
excessive current will be drawn until the
thermal fuse opens.
The external port, labeled EXT, is not meant to
be used with the PS12LA. The primary power
source is the charging source, and the
secondary power source is the internal lead
acid battery. Connecting a lead acid battery to
the external source is the same as connecting
two lead acid batteries in parallel, causing one
battery to drop voltage and the other to raise
voltage. Alkaline batteries connected to the
external port would be charged by the charging
source, which can cause an explosion.
CAUTION: Do not use the external port,
labeled EXT, with the PS12LA.
Monitor the power supply using datalogger
Instruction 10. Users are strongly advised to
incorporate this instruction into their data
acquisition programs to keep track of the state
of the power supply. If the system voltage level
consistently decreases through time, some
element(s) of the charging system has failed.
Instruction 10 measures the voltage of the lead
acid battery. External power sources must be
disconnected from the CR10T and charging
circuit in order to measure the actual lead acid
battery voltage.
TABLE 3-8. PS12LA Battery and AC
Transformer Specifications
Lead Acid Battery
Battery type
Yuasa NA 7-12
Float life @ 25
°
C
5 years typical
Capacity
7.0 amp-hour
Shelf life, full charge
Check twice yearly
Charge time, (AC Source)
40 hr. full charge
20 hr. 95% charge
AC Transformer
Input:
120V AC, 60 Hz
Isolated output:
18V AC @ 880 mA
max.
3.4.3.3 PS512M Voltage Regulator with Null
Modem Ports.
The PS512M 12 Volt Lead Acid Power Supply
with Charging Regulator and Null Modem Ports
is used when 5 volts is needed to power CSI's
external modems through the 9-pin serial ports.
The PS512M supplies 5 volts to pin 1 of the 9-
pin null modem ports, otherwise the capabilities
and functions are identical to the PS12LA. A
common use for the PS512M is in
radiotelemetry networks. The PS12LA cannot
be modified to the PS512M. The maximum
current drain on the 5 volt supply of the PS512M
is 150 milliamps.
3.5 RF232T BASE STATION
3.5.1 RF232T INTRODUCTION
The RF232T Base Station provides a "single box"
desktop base station with the following features:
•
Internal RF modem.
•
25-Pin RS232 port for connection to IBM PC.
•
110 VAC/12 VDC transformer and mount
for the base radio.
•
Easy access to radio for antenna cable
connection.
