Studio Technologies 93 - Manual (Page 9)

Model 93 User Guide Issue 1, January 2008
Studio Technologies, Inc. Page 9
Model 93 automatically powering down. With
a low battery condition, normal operation
can’t take place unless an external source of
nominal 12 volts DC is applied. This power
source will allow Model 93 operation as well
as charging the internal battery. Maintaining
the external 12 volt source for up to 24 hours
may be required to fully recharge the battery.
There are four ways that the Model 93 can
be “powered down.” One is manual and
three are automatic. The power on/off but-
ton can be used to manually halt the unit’s
operation; simply tap the power button.
Pressing and holding the on/off button while
the unit is operating will cause a change in
the unit’s operating mode rather than turning
off the unit.
The three automatic power down methods
are inactivity, master/slave command, and
low battery voltage. To maximize the Model
93’s battery operating time, automatic shut-
down will occur after ten minutes of inactivity.
Technically, inactivity is defined as a continu-
ous 10-minute period in which none of the
buttons are pressed. The only exception to
the inactivity timer is if the unit is operating
in the slave mode and data is present on
the master/slave data link. In this case, for
the Model 93 to automatically power down
requires that a power down command be re-
ceived by way of the master/slave data link.
The final way that the Model 93 will power
down is if a low battery voltage condition is
detected. Under software control, the battery
voltage is continually monitored. A measure-
ment of lower than 10 volts will result in an
automatic power down.
For operator convenience, upon power down
three operating conditions are saved in non-
volatile memory: operating mode, connector
mode, and channel/pin mode.
Powering the Model 93
Internal Battery
The Model 93’s enclosure includes an inter-
nal 12 volt, 1.3 amp-hour, sealed lead-acid
rechargeable battery. This type of battery
was selected for two reasons: its ability to
supply peak current and long cumulative
operating time. The LED-based displays
used in the Model 93 offer several nice
operating characteristics as well as one
limitation. The first positive is that they are
very rugged and should be able to meet the
often-harsh conditions of field production
settings. A second is that they provide a
clear indication in low-light conditions. How-
ever, as with most things one must take the
good with bad. The downside of LED dis-
plays is that they require high peak currents
for effective operation. Standard one-use
(disposable) batteries, such as the ubiqui-
tous 1.5 volt AA style, would simply not be
suitable. The Model 93’s internal lead-acid
battery doesn’t have a problem supplying
the required peak current.
The energy capacity of the Model 93’s inter-
nal battery is such that cumulative operating
time in excess of eight hours can be expect-
ed before recharging is required. In actual
applications it can be expected that it will be
weeks, or even months, between required
charges.
External Power Source
An external source of nominal 12 volts DC
is required for Model 93 operation and bat-
tery charging. The exact voltage value isn’t
critical; anything in the range of 10 to 15
volts is acceptable. Proper battery charging
will always take place because circuitry con-
tained within the Model 93 converts the in-
coming voltage to the required nominal 13.8
volt DC charge voltage. A minimum of 150
milliamperes is required for operation and