08/09/09

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ES51983

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.

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

4000000

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

Full Scale