3 3/4 AUTO DMM
Continuity check shares the same configuration with 400.0Ω manual resistance
measurement mode, but with buzzer output to indicate continuity. The buzzer generates a
2KHz sound whenever the digit number less than 25Ω. Because the cycle time of
measurement is only 70ms, the least significant digit will not display.
1.5 Diode Measurement
Diode measurement mode shares the same configuration with 4.000V manual voltage
measurement mode. If the test circuit is open or the voltage drop between the two ports
of the device (diode) under test is larger than 2V, the LCD panel will show “OL”. The
buzzer generates a 2KHz sound whenever the digit number is less than 0.25V. Because
the cycle time of measurement is only 70ms, the least significant digit will not display.
1.6 Auto power off
ES51983 has a default auto power off function. If the meter idles for more than 10
minutes, the chip automatically turns the power off. When this happens, the state of the
meter is saved. In order to disable auto power off function, power on the meter when
any of the push function, except for HOLD, is pressed down. In addition, when RS232
output is active, the auto power-off function is also disabled. The APO sign on the LCD
panel indicates whether the auto power-off is enabled or not.
ES51983
Note:
Powering on the meter while pressing HOLD turns on all LCD segment until
HOLD is pressed again.
1.7 Frequency counter
The time base of the frequency counter is derived from an external crystal oscillator by
T
counter
=
4000000
F
osc
where f
osc
is the frequency of the crystal oscillator. Thus, the counter has a 1 second time
base when a 4MHz oscillator is used. The frequency counter can select the proper range
automatically or manually. Auto-range operation extends over five decades, from 4KHz
to 40MHz The following table summarizes the full scale range of the frequency counter.
Range
8
Full Scale
11/01/05
CYRUSTEK [ Cyrustek corporation ]
