Time Electronics 1024 DC Current Calibrator - Manual (Page 6)

6
1024 Technical Manual 6
e) Battery Level
The battery (or mains power supply PU2) output is continuously monitored on a front panel
indicator which also serves as a supply ‘on-off’ indication. A minimum mark indicates when
the batteries need recharging.
f) Range
One of the five output ranges can be selected.
g) Digit Switches
A 5-decade thumbwheel switch enables the output current level to be set with a resolution of
0.01% of full scale.
h) Voltage Limit
An L.E.D. indicator shows when the 1024 is unable to supply sufficient drive voltage to
maintain the set output current.
Example: The 1024’s maximum drive voltage (voltage capability) is 15 Volts. This means
that it is able to supply a current of 1mA into 15K ohms but NOT 1mA into 16K ohms. In the
latter condition the voltage limit indicator would display.
The above is an example and applies similarly for any product of current and load
resistance that exceeds 15 volts. Non-resistive loads are still bound by the same output
voltage limit with the indicator displaying when the voltage at the output terminals reaches
about 15V.
Note:
When the 1024 is operated from partly discharged batteries, the voltage limit is reduced to a
minimum of about 10V for nearly fully exhausted cells. The battery level indicator gives a
clear indication of battery state.
i) Null Meter
Scaled 0 to 25 for displaying the difference current when the 1024 is used in the null mode.
j) Sensitivity Control
A continuously variable control for adjusting the null meter sensitivity, range of adjustment is
from 25mA minimum (fully anticlockwise) to 25uA maximum (fully clockwise).
k) Source - Null Switch
A two position toggle switch which selects the mode of operation. In the SOURCE position
the 1024 operates as a current source while the null position allows measurement of
current.
Important Note:
Under no circumstances must an additional voltage be connected in series with the
1024 output in an attempt to increase the voltage capability. This practice will cause
damage to this 1024’s output circuitry.
Under certain conditions the voltage capability can be increased to a maximum of
50volts. This requires special circuit modifications and is only applicable to certain
ranges. Please consult Time Electronics (or their authorised dealer) for information.