RADAR TEST SET
THEORY OF OPERATION - Continued
The 12 Volt input from the AC adapter powers a 1.5 amp constant current source for charging the battery.
The current source is controlled by an integrated circuit that checks for the presence of a battery, limits the
charging temperature range, and terminates charging when the battery is fully charged. The IC determines
that a battery is fully charged by detecting the small drop in battery voltage which occurs once the NiCad or
NiMH batteries are fully charged by constant current. Charging is terminated if excessive battery temperature
is detected. Operation of the charger is inhibited when the discharge cycle is active.
The discharge load resistor is switched by a control circuit that monitors the battery voltage under load.
Discharge is initiated by the front panel switch and is maintained until the battery voltage drops under 6 volts
(1 volt per cell). This provides nearly complete discharge without discharging to the point of potential battery
damage. The discharge circuitry is battery powered, so connection to the AC adapter is not required. If the
AC adapter is connected, the charge cycle will begin automatically once the batteries are fully discharged.
This allows a partially discharged battery to automatically be fully discharged then charged, preventing NiCad
memory effects. If the AC adapter is not connected, battery discharging will terminate automatically once
END OF WORK PACKAGE