TTI 1906 DATASHEETS

THURLBY THANDAR INSTRUMENTS

1906

5½ digit high performance multimeter

Full autoranging, True RMS, RS-232 & GPIB interfaces

5½ digitperformance at a 4½ digit price

higher resolution, accuracy & functionality

Greater resolution and
accuracy

The 1906 is a true 51/2digit meter with a
scale length of
This gives it not just superior resolution

relative to 4
higher effective accuracy as well.

Thediagram showshow theeffective ac
curacy varies with reading after taking
into account the fixed errors. Over a
range of voltages, the 1906 is around
four times more accurate than a typical

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/2digit meter.

4

± 210,000 counts.

1

/2digit meters, but much

Greater sensitivity and
higher input impedance

With a maximum resolution of 1µV, 1mΩ
and 1nA, the1906 is ten times more sensi
tive than a 4

This extra sensitivity enables accurate
measurements to be made in areas previ
ously impossible such as thermocouple
junctions, switch contact resistance or ca
pacitor leakages.

Industry standard 10MΩ input impedance
appliestoall dcvoltageranges, butthelow
est two can alternatively be selected at
greater than 1000MΩ impedance to elimi
nate errors when measuring high imped
ance circuitry.

1

/2digit meter.

True RMS ac functions

The 1906 provides True RMS ac response

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whichgives accurate measurementsregard
less of the waveform shape.

The wide bandwidth voltage attenuator
provides high accuracy within the audio
band and gives extended response to
avoid distortion when measuring switching
waveforms.

Auto or manual ranging

The 1906 offers fully automatic ranging
on all functions including current. Alter
natively any range can be selected and

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held manually.

4 terminal Ohms for

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improved stability

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Resistance measurements can bemade
in either 2 terminal or 4 terminal mode.
High impedance sensing ensures that
the meter switches automatically be

­tween modes.

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For low resistance measurements, 4 ter

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minal modeoffers much higher accuracy
and repeatability.

Theresistance functionalso providesse
lectable audible continuity as well as di
ode test capabilities.

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Closed case calibration

The 1906 stores its calibration constants
in permanentmemory (EEPROM). Con­sequently it can be recalibrated without
ever opening the case.

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5½digit scale length ( 210,000 counts)

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0.012% basic one year accuracy

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1uV, 1m and 1nA resolution, 4 terminal Ohms

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Full automatic or manual ranging

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True RMS ac functions, wide ac bandwidth

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Full set of current ranges from 200µA to 10A

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Wide range of computing and data logger functions

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Fully programmable by RS-232 or GPIB interfaces

Storage of front-panel
set-ups

The 1906 can store up to six front panel
set-ups in non-volatile memory.

In addition to the range and function
each set-up defines the active comput
ing or logging functions along with their
parameters.

This facility is particularly valuable when
similartests needto berepeated atinter
vals.

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built-in computing & data logging

full bus programmability

Single key convenience
functions for ease of use

Press the “null” key and the present dis
played reading is stored and subtracted
from all future readings.

This powerful feature has a host ofuses
such as removing test lead resistance,
observingdeviation levels, ormeasuring
relative to alternative voltage points us
ing a fixed ground lead connection.

Touch and Hold

Thetouch andholdfunction isinvaluable
when taking measurements in awkward
situations whereit may be difficult tosee
the multimeter display.

Withtouchand holdselected,the display
is automatically frozen every time a sta
ble reading is achieved. A further press
of the T/HOLD key un-freezes the dis
play.

Digital filtering for better
noise performance

The 1906 uses non-linear digital filtering
which is highly effective in eliminating
unwanted noise, but responds rapidly to
a change in the reading.

When working with very noisy or unsta­blemeasurements, thecharacteristicsof
thedigitalfilter canbeadjusted tosuitthe
application.

Full protection for the
instrument and the user

The 1906 incorporates extensive protec
tion against damage from accidental
overloads on all ranges including 10
Amps.

In additionthe 1906 meets the stringent
safety requirements of IEC348 and
IEC1010-1 for measurements up to
1kV.

Linear scaling with offset
(Ax+b)

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This function enables a reading to be
multipliedby a scalefactor (A) andfor an
offset (b) to be added or subtracted.

Thismeans, forexample, thatthe electri
cal output of a transducer can be scaled
to give a direct readout of the physical

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parameter e.g. temperature or weight.
It is particularly useful with 4-20mA cur

rent loops.

Limits comparison

This function enables the reading to be
tested against high and low limits set by
the user.

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­The display then shows a code of H

(high), L (low) or P (pass) at the end of
the display.

Percentage deviation ( %)

This function enables the meter to dis­playthepercentage amountbywhich the
readingdiffers froma nominalvalue cho­sen by the user.

It is invaluable for measuring tolerance
or stability.

Min-Max storage

The Min-Max function stores the highest
and lowest values of a set of readings.

This facility has many uses such as
checking for power supply glitches, re

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cording peak temperature excursions
and avoiding “missed” readings when
using the Logger function.

Logarithmic
measurements (dB)

Thisfunctionallows measurementstobe
displayed in the form 20log
zero reference scaling enables voltages
to bedisplayed in dBV ordBm relative to
any required impedance.

X. Built-in

10

Automatic data logging

The1906 canstore upto 100readingsat
any requiredtime interval from1 reading
per second up to 1 reading every 3
hours.

A simple recall sequence allows the

­readings to be scrolled onto the display

whenever required. Alternatively results
can be downloaded using the RS232 or
GPIB interfaces.

­As a result, tedious time related meas

urement sequences can be handled
automatically without disrupting your
work.

Manual storageof readings is also avail
able eliminating the need for paper and
pencilwhen makingaseries ofmeasure
ments.

Storage can also be triggered from the
RS-232 or GPIB interfaces.

Full bus control via
RS-232 or GPIB

The 1906 is designed for complete bus
control. Every function of the instrument
canbecontrolled usingeither theRS-232
interfaceorthe GPIBinterface (optional).

The RS-232 interface, which is fitted as
standard, iscompatible with theTTi ARC
system.

The ARC system (Addressable RS232
Chain) enables up to 32 instruments to

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be “daisy-chained” togetherand to be in
dividually addressed and controlled us
ing a single RS232 port of a PC.

Compatible with IEEE-488.2

The GPIB interface is an option. When
installed, a rear panel switch allows the
user to choose between RS232 or GPIB
control.

The GPIB interface conforms fully with
bothIEEE-488.1and IEEE-488.2. The.2
standard contains many enhancements
which are particularly important when
programming systems incorporating a
number of instruments.

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Using the null key allows gains and
losses to be measured directly.

Technical Specifications

INPUT CHARACTERISTICS

Input Current: < 100 pA.
DC NMR: > 60dB at 50/60Hz.
1k Unbalanced

CMR:

ACCURA CY

Accuracies apply for 1 year 18oC to 26oC. Temperature coefficient outside
these limits is <0⋅1 x quoted range accuracy per
accuracy is 1 hour.

DC VOLTS

Range

200mV

2V

20V

200V

1000V

RESISTANCE (OHMS)

Range

200

2k

20k

200k

2M

20M

Max open circuit voltage 3⋅5V. Diode Test on 2k range.
Audible continuity check available on all ranges.

AC VOLTS (True RMS)

Range

200mV

2V

20V
200V
750V

Additional error at crest factor=3 typically 0⋅7%. Input impedance 1MΩ /
<100 pF any range. Max input 750V rms, 1kV peak, any range.
Accuracies apply from 10% to 100% of full scale.

DC AMPS

Range

200µA0⋅08% + 12d

2mA

20mA

200mA

10A <2000mA

> 120dB at DC/50Hz/60Hz, DC ranges;
> 60dB at DC/50Hz/60Hz, AC ranges.

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C. Warm-up time to rated

Accuracy(±)

0⋅017% + 3d
0⋅012% + 3d
0⋅019% + 3d
0⋅019% + 3d
0⋅019% + 3d

Accuracy(±)

0⋅025% + 4d 1mΩ 1⋅5mA
0⋅019% + 3d 10mΩ 1⋅5mA
0⋅019% + 3d 100mΩ 0⋅4mA
0⋅019% + 3d 1Ω 40µA

Res. Input Impedance Max Input

1µV

10µV

100µV

10MΩ or >1GΩ

(Hi Z mode)

10MΩ

1kV DC or

AC Peak

any range

1mV

10mV

Resol-

ution

Max. Measur

ing Current

Max. Input

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300V DC or

RMS continu

ous any

Ohms input

any range

0⋅022% + 3d 10Ω 4µA

0⋅07% + 3d 100Ω

Accuracy(±)

400nA

45Hz - 5kHz 5kHz - 10kHz 10kHz-20kHz 20kHz-50kHz
0⋅2% + 150d 0⋅2% + 250d
0⋅2% + 150d 0⋅2% + 250d 0⋅5% + 300d
0⋅2% + 150d 0⋅2% + 250d 0⋅5% + 300d
0⋅2% + 150d 0⋅2% + 250d 0⋅5% + 500d
0⋅2% + 150d

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Accuracy(±)

0⋅08% + 12d
0⋅08% + 12d
0⋅08% + 12d
0⋅08% + 12d

>2000mA

0⋅12% + 12d

3% + 500d -

3% + 1500d
2% + 1000d

Resol

Voltage

ution

Burden

1nA 300 mV

10nA

max

100nA

1µA
100µA 650mV
100µA

max

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Max. Input

1A, 300V

fuse pro

tected

10A, 300V

fused

AC AMPS (True RMS)

Range

Accuracy(±) 45 Hz - 1 kHz

200µA0⋅37% + 100d

2mA

20mA

200mA

10A <2000mA

>2000mA

Additional error at crest factor=3 typically 0⋅7%. Accuracies apply from
10% to 100% of full scale.

0⋅37% + 100d
0⋅37% + 100d
0⋅37% + 100d
0⋅37% + 100d

0⋅4% + 100d

Voltage
Burden

300mV

max

650mV

max

DISPLA Y

Display Type: 13mm LED, 8 digit.
Scale Length: Selectable 5½ digit or 4½ digit.
Reading Rate: 3 readings/sec (5½ digit).

Overrange:
Overflow:
Annunciators: LEDs for range, function and program modes.

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COMPUTING FUNCTIONS

Null: Operates over full range; values can be stored for
Digital Filter: 10 options, including optimised default values for
Touch & Hold: Reading is held when stable.

% DEV: Displays % deviation from entered reference value.
dB: Displays measurement in dB relative to 1V, 1mA,

Ax+B: Linear scaling of results, with offset.
Limits:

Min/Max: Minimum and maximum reading stored.
Data Logger: Manual or automatic storage of 100 measurements,

10 readings/sec (4½ digit).
Displays OL if input too great for range.
Displays OFLO if calculated result overflows display.

every function.
each range and function.

1kΩ or user entered value, or in dBm.
Reading displayed with H, L, or P (pass) with respect

to user-defined high and low limits.

Storage interval 1s to 9999s.

INTERF A CES

RS232: Baud rates 300, 1200 or 9600. Complies fully with

GPIB (Optional): Fully complies with IEEE-488.1 and IEEE-488.2

the ARC (Addressable RS232 Chain) interface stan
dard. Address selectable from the front panel.

GENERAL

AC Input: 220 to 240 volts ±10% or 110 to 120 volts ±10%
Consumption: 25VA max.

Operating Range: +5
Storage Range: -40

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Environmental: Indoor use at <2000m, Pollution Degree 1.
Safety: Complies with EN61010-1.
EMC: Complies with EN61326.
Size: 260(W) x 88(H) x 235(D)mm, excl. handle and feet
Weight:

Thurlby Thandar Instruments Ltd. operates a policy of continuous devel
opment and reserves the right to alter specifications without prior notice.

50/60Hz, Installation Category II.

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C to +40oC, 20% to 80% RH

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C to +60oC

2⋅2kg.

Max Input

1A, 300V

fuse pro

tected

10A, 300V

fuse pro

tected

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Designed and built in Europe by:

Thurlby Thandar Instruments Ltd.

Glebe Road, Huntingdon. Cambs. PE29 7DX United Kingdom (UK)

Tel: [phone] Fax: [phone]

Email: [e-mail] Web: http://www.tti-test.com

82100-0047 Issue 3