LASCAR V 125 User Manual

V 125

3½ Digit LCD Voltmeter Module

PRODUCT DESCRIPTION

This low cost compact LCD voltmeter module is ideally suited for high volume applications. It features an exceptionally
large display ina miniaturepackage and includesauto-zero anduser-selectable decimal points. The module is suppliedwith
a panel mountingbezel.

FEATURES

• Low Cost

1

REAR VIEW

8

• 12.5

mm (0.5") Digit Height

• 200mV d.c. Full Scale Reading

• 1mA (typ) @ +9V d.c. Power Supply

•

Auto-zero and Auto-polarity

• User Selectable

•

Supplied with Mounting Bezel

Decimal Points

TYPICAL APPLICATIONS

• High Volume, Low Cost Systems

• Power Supply Monitoring

ORDERING INFORMATION

Stock Number

Standard Meter V 125

• Panel-Mount Indication

ELECTRICAL SPECIFICATIONS

Specification Min. Typ. Max. Unit

Accuracy (overall error) * 0.25 % (±3 counts)
Linearity 0-1000 reading ±3 counts

Sample rate 3 samples/sec
Operating temperature range 0 50 °C
Temperature stability 300 ppm/°C
Supply voltage 7.0 9 12 V d.c.
Supply current 1 2 mA

* To ensure maximum accuracy, re-calibrate periodically.

0-2000 reading counts

±5

SAFETY

To comply with the Low Voltage Directive(LVD 93/68/EEC), inputvoltagestothemodule’spinsmustnotexceed
60Vdc. The usermustensurethat the incorporation of thepanel meter into theuser’s equipmentconforms to the
relevant sections of BS EN 61010 (Safety Requirements for Electrical Equipment for Measuring, Control and
Laboratory Use).

LASCAR ELECTRONICS LTD.
MODULE HOUSE
WHITEPARISH
WILTSHIRE SP5 2SJ
UK
TEL: [phone]
FAX: [phone]
E-mail: [e-mail]

LASCAR ELECTRONICS INC.
PO BOX 50727
PALO ALTO
CA 94303-0727
USA
TEL: [phone]
FAX: [phone]
E-mail: [e-mail]

www.lascarelectronics.com

LASCAR ELECTRONICS (HK) LIMITED
FLAT C, 5/FL., LUCKY FTY. BLDG.
63-65 HUNG TO ROAD
KWUN TONG
KOWLOON
HONG KONG
TEL: [phone]
FAX: [phone]
E-mail: [e-mail]

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V 125

3½ Digit LCD Voltmeter Module

DIMENSIONS

Panel thickness: 1.0 - 3.0

24.4 (0.96)

50.0 (1.97)

PANEL FITTING

Panel

Meter

All dimensions in mm (inches)

(0.04 - 0.12)

dia 2.5 (0.1)

21.4 (0.84)

20.4 (0.80)

14.0 (0.55)

45.0 (1.77)

41.5 (1.63)

50.0 (1.97)

40.7 (1.60)

31.0 (1.22)

2.5(0.1) dia

Fixing Clip

5.3 (0.20)

1.6 (0.06)

1.27 (0.05)

Pin Pitch 2.5 (0.1)
Pin positions are symmetrical
about the vertical centre line

Bezel

1

2 4

FUNCTIONAL BLOCK DIAGRAM

V+

Vref

CAL

COM

INHI

INLO

+

_

A/D

XDP

Fastener

3

PIN CONFIGURATION

CAL

REAR VIEW

V+V-INHI

1

L1

INLO

XDP

DP1

DP2

DP3

(rear view)

8

V-

DP321

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V 125

CIRCUIT DIAGRAM

1

V+

R1

300k

R2

1M

3

INHI

INLO

4

L1

V+

R6
100k

R5
3k

100nF

C3

68nF

220nF

100nF

R3

3½ Digit LCD Voltmeter Module

1

C1

C2

C4

100k

C5
100pF

V+

27

INT

28

BUF

29

A/Z

31

IN HI

30

IN LO

32

COM

IC1

34

CREF+

33

CREF-

35

REF LO

36

REF HI

40

OSC1

39

OSC2

38

OSC3

524

a1

423

b1

321

c1

220

d1

819

e1

625

f1

722

g1

12 28

a2

11 27

b2

10 17

c2

916

d2

14 14

e2

13 1

f2

25 26

g2

23 3

a3

16 2

b3

24 12

c3

15 11

d3

18 10

e3

17 4

f3

22 5

g3

19 8

bc4 ab4

20 7

POL

21 15

BP

V-

TEST

37

26

a1
b1
c1
d1
e1
f1
g1
a2
b2
c2
d2
e2
f2
g2
a3
b3
c3
d3
e3
f3
g3

POL
COM

LCD1

LOBAT

DP1

DP2

DP3

199.9
18

19.99
13

1.999
9

6

6

DP1

7

DP2

8

DP3

R81MR7

R9
1M

1M

R4

1.5k

2

V-

R10
100k

Q1
3904

PIN FUNCTIONS

1. V+ Positivepower supplyconnection.

2. V- Negative power supply connection.

3. INHI Positivemeasuring inputwith referencetoIN LO.

4. INLO Negative measuring input with referenceto INHI.

5. XDP Connect to DP1, 2 or3 todisplayrequireddecimal point.

6. DP1 Connect to XDP to displayDecimal Point 1(199.9).

7. DP2 Connect to XDP to displayDecimal Point 2(19.99).

8. DP3 Connect to XDP to displayDecimal Point 3(1.999).

Solder Links:

L1 Normally Closed, connects COMto INLO.

V+

R11
100k

Analogue inputs must be no closer than 1V
to either the positive or negative supply.

5

XDP

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V 125

SCALING

Two resistors Ra and Rb
may be used to alter the
full scale reading (FSR) of
the meter - see table. The

Voltage

Vin 200V 1M 1k

meter will have to be re­calibrated by adjusting the
calibration potentiometer
on the rearof the module.

Current

Iin 20mA 0R 10R

*Ensure that Ra is rated for high voltage use.

APPLICATIONS

Do not connect more than one meter to the same power supply
if the meters cannot use the same signal ground. Taking any
input beyond thepower supply railswill damage the meter.

+7.0 to +12V +7.0 to +12V

11

V+

FSR Ra Rb

2V 910k 100k

20V 1M 10k

2000V* 1M 100R

200 A 0R 1k

µ

2mA 0R 100R

200mA 0R 1R

3½ Digit LCD Voltmeter Module

Ra

+

Vin or inI

-

Normally
SHORTED
Cut to
OPEN

V+

Rb

INHI

INLO

Normally
OPEN
Solder to
SHORT

L1

V 125

V-

DP1 DP1

XDP XDP

±200mV

+

-

33

IN HI

44

IN LO

22

0V 0V

Measuring an input voltage referenced to a floating supply,
i.e. the input voltage and the meter's power supply are
isolated from each other. Check Link L1 is closed.

+3.5 to +6.0V

1

V+

L1

V 125

V-

DP1

XDP

±200mV

+

-

3

4

IN HI

IN LO

2

66

5

I+

I-

Measuring a current referenced to a floating supply, i.e. the
current being measured and the meter's power supply are
isolated from each other. Check Link L1 is closed.

IN HI

IN LO

L1

5

V 125

V-

6

5

-3.5 to -6.0V

Measuring a single ended input referenced to supply, i.e.
the input voltage and the meter's power supply share the
same 0V rail. Check Link L1 is open.

Specifications liable to change without prior warning V 125 Issue 3 January/2002 M.C. Applies to V 125/2

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