Specifications

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In order to do this, two issues had to be considered. First, the charging circuit
must be disconnected. Secondly, the issue of switching the voltage source of the
voltage regulators, and thus the rest of the device had to be considered. Since
the circuit is powered from the battery for the portable configuration, a change to
the external voltage source must be made in order for the control unit to have
power without the battery.
One option considered was to create a type of voltage comparator, which would
be capable of automatically detecting the higher of two voltages, and “switching”
to the greater voltage. However, this would likely not be the most efficient route
since it would create extra circuitry to handle a case which would not be
encountered under the expected usage plan. Since this board will be switched
during manufacturing, the board’s role as a portable board or control unit board is
decided a single time, by the device manufacturer (not the user). As such, a
jumper system made more sense. By changing a few jumpers at certain
locations, the circuit could be adjusted for either the portable or base unit
purpose. The summary of the jumper configurations is listed in Table 3.7.2-1.
Using these settings will yield the desired configuration by disconnecting and
connecting appropriate portions of the circuit.
Jumper
Open/Closed if
Portable?
Open/Closed if
Control?
J1
Closed
Open
J2
Open
Closed
J3
Closed
Open
Table 3.7.2-1: Jumper configurations to achieve either portable or control board
mode.
Thus, not only can the boards be used for both circuits, but it can be done
cheaply and reliably.
3.8 Enclosure
Our development for the enclosure design initiated after the research of our
resource availability and options. It is our goal to make an attempt on our
enclosure housing for the hand-held unit. Three preliminary drawing were
created and documented below each with its purpose.
Concept I is based on the number 8, representing our group number 8. It is
design with the purpose to grab one’s attention right away. This concept will be