-24 Volt Supply; Battery Charging - Racal Instruments 9916 Workshop Manual

-24 Volt Supply
4.59 The 1 MHz signal from 1C4/6 is used to clock IC14o. This is connected to divide
by two, so that 07 is driven at 500 kHz, The oscillation in Tl is rectified by 06
-_md D7, and boosts the +5 vo! ts to +24 vol ts to supp ly IC26. The supply is present only when
the
'A'
Channel is selected as in other conditions IC14a is held in the cleared state.
-~1-2
Volt Supply
4.60
A +2 volt supply is obtained for IC4 from the -+5 volt supply via the regulator 014.
Q14 is controlled by 015, which obtains its reference voltage from IC4/11.
Battery Charg ing
4.61 If fitted, the batteries receive trickle charge whenever the instrument is
operating from a
I
ine power supply. Each battery is connected between the
-+5
-volt and -5 volt rails, as shown in Fig. 4.2. The diodes D26 and D27 prevent the batteries
discharging if the supply is disconnected with the instrument switched on.
+
5V RAIL
' I
BATTERY 'A'
I
+
5V
o
l(
WITCH
52
LINE POWER
CHARGE
~
52e
027
R74
BATT
0
POWER
RI3B
7
BATTERY'S'
I
-5V
o
-5V
RAIL
026
R128
S2d
4
~_~_----,-3-e
S 29
, 12
fvS5I
CI01
"W~GA~~
EM
ITTER
R133
5
o
Battery Charging Circuit
Fig.4,2
4-10
9916 Vol. 2