APPLICATION
22
ELECTRONICS DESIGN LAB
The technician or engineer working in an engineering laboratory
requires a dc power supply to power breadboard and prototype
circuits. This power supply is ideal because it monitors output
current, output voltage, limits current to protect the circuit, is
adjustable over a wide range, and has excellent regulation and very
low ripple.
Use of the instrument in an engineering laboratory is very
similar to that described for servicing electronics equipment and
modules, except that lower currents may be prevalent when
powering individual circuits. The current limiting feature is very
valuable in this application because it can protect unproven circuits
from damage.
ELECTRONICS EDUCATION
The student in an electronics curriculum may use the power
supply for powering equipment and circuits as previously
described for all other applications. In addition, the power supply
can be used in the classroom laboratory to conduct experiments in
fundamental electronics. In learn ing Ohm’s law, for example, the
relationships of resistance, current, and voltage are easily
demonstrated by the use of a power supply.
BATTERY CHARGING
The power supply can be used as a battery charger to
restore the charge in rechargeable batteries such as lead-acid,
nickel-cadmium, and some alkaline types. Refer to the
battery manufacturer’s charging specifica tions for proper
voltage and current settings. Charging information is
sometimes printed on the batteries. Battery charging, at least
initially, requires the constant current mode of operation.
Before connecting the power supply to the battery, preset the
VOLTAGE
controls to the fully charged terminal voltage
specified by the battery manufacturer. Turn off the power
supply while connecting the battery. Observe proper polarity
and connect as for constant current operation. Adjust the
CURRENT
control for the maximum charging current
specified by the battery manufact urer. (If the maximum
charging current is greater than the power supply’s maximum
load current, set the
CURRENT
control to maximum). The
CC
indicator will light and the battery will charge at the
preset current limit. As the battery approaches full charge, its
terminal voltage will approach that of the power supply
output and the charging current will taper off. The power
supply may automatically switch to
CV
(constant voltage)
operation. When this occurs, the power supply will continue
to provide a trickle charge.
