Mode Selection; Choice Of Range; Measurement Value Display - Hameg HM8012 Handbuch

(16) AUTO (pushbutton)
Pushbutton for switching the AUTO range
selection to the MANUAL range selection and
vice versa.
In AUTO mode, the choice of range is determined
automatically by the unit. This is the default mode
when the unit function is changed (V, mA, Ω, dB).
In MANUAL mode, the choice of range is left to
user initiative using the keys (12) and (13).
(17) Unit display zone (LED)
This zone contains a display of the measurement
units. It also identifies the function selected by
pressing the (20) or
(18) AC-DC (pushbutton)
This key is used for selecting the measurement
mode (DC, rms AC or rms AC + DC).
Indicators below indicate the measurement
mode:
DC : measurement of DC voltages
AC : measurement of RMS AC voltages
DC and AC : measurement of RMS AC+DC
voltages.
(19) (pushbutton)
Pushbutton for selecting the next function.
(20 (pushbutton)
Pushbutton for selecting the previous function.
On startup, the unit switches automatically to the
DC voltmeter, AUTO mode function.
Choice of multimeter function
The and keys can step through all the
multimeter functions one by one, i.e., in order:
DC or AC voltages. Input on the V/Ω/T°/dB
and COM connectors.
The measurement of DC or AC voltages in
decibels (reference 1mΩ/600Ω). Input to V/
Ω/T°/dB and COM connectors.
DC or AC current up to 500 mA. Inputs on
mA/µA and COM connectors.
DC or AC current, 10 A range. Inputs on the
A and COM connectors.
Resistors. Inputs V/Ω/T°/dB and COM
connectors.
Temperature in degrees Celsius. Connection
of probe to V/Ω/T°/dB and COM connectors.
Temperature in degrees Fahrenheit.
Connection of probe to V/Ω/T°/dB and COM
connectors.
Diode test. Inputs on V/Ω/T°/dB and COM
connectors.
On each press, the new function is indicated by
an LED corresponding to the unit of the quantity
to be measured. It is possible to move from one
Subject change without notice
(19) key.
function directly to any other function by a
successive series of pressings.

Mode selection

For current and voltage modes, the AC-DC key
is used for choosing between DC voltage
measurement, AC or AC + DC true rms voltage
measurement.

Choice of range

In manual mode,
switching between the various measurement
ranges. The measurement ranges are split into
decades. After each range change, a code
appears indicating the new range being used. This
code is in LX form, where X is a value that may
vary from 1 to 6 depending on the range and
function and L1 is the lowest range.
During measurements of unknown voltages or
currents, first choose the highest measurement
range, then switch to the range giving the most
favorable display.
The automatic mode is active after instrument
turn-on. Depending on the unknown input
magnitude, the instruments selects the range for
optimum resolution.
In automatic mode, the unit itself decides on the
range selection. Ranges are changed with some
hysteresis to avoid repetitive switchover during
transitions between two ranges. Change to the
higher range is obtained when the value exceeds
50,000 counts. Change to the lower range is
obtained when the value drops below 4,900
counts. It is possible to know which range has
been selected by the unit by temporarily
deactivating the AUTO mode so that the range
indication code appears fleetingly.

Measurement value display

Measurement values are represented by 7
segment LED's display associated with one LED
for the negative sign. The maximum value of the
1st digit is 5: this corresponds to a 4 3/4 digit
display with a 50,000 counts measurement
capacity. A minus sign appears in front of the
figures when, during DC measurements, the
positive polarity of the measured value is on the
COM terminal. With the inputs short-circuited,
the display indicates (depending on the
measurement range) value zero ± 2 digit. When
the range is overrun, the display shows "OFL"
and an audible beep is emitted repeatedly. For
the resistance measurement function, the
exceeding of the capacity (> 50MΩ) generates
the "OPEN" message.
If the multimeter is not connected to a circuit,
the display indicates random values due to the
very high input impedance for ranges of 500mV
and 5V.
the and keys are used for
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