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LH2H 

Hour Meter

3

Non-voltage input type

• Never apply voltage to the non-voltage input type. This

will damage the internal elements.

Since the current flow is very small from the start input

and reset input terminals (  and   on panel mounting
type and   to   and   to   on PC board mounting
type) please use relays and switches with high contact
reliability. When inputting with an open collector of a
transistor, use a transistor for small signals in which I

CBO

is 1 μA or less and always input with no voltage.

• When wiring, try to keep all the input lines to the start and

reset inputs as short as possible and avoid running them
together with high voltage and power transmission lines
or in a power conduit. Also, malfunctions might occur if

the floating capacitance of these wires exceeds 500 pF

(10 m 

32.808 ft

. for parallel wires of 2 

mm

2

 

). In particular,

when using shielded wiring, be careful of the capacitance
between wires.

Voltage input type

• Be aware that applying more than 30 V DC to start input

terminals   and  , and reset input terminals   and
will cause damage to the internal elements.

For external resetting use H level (application of 4.5 to

30 V DC) between reset terminals   and   of the rear
terminals. In this case, c to terminal   and – to
terminal  . This is the valid polarity; therefore, the hour
meter will not work if reversed.

• When wiring, try to keep all the input lines to the start and

reset inputs as short as possible and avoid running them
together with high voltage and power transmission lines
or in a power conduit. Also, malfunctions might occur if

the floating capacitance of these wires exceeds 500 pF

(10 m 

32.808 ft

. for parallel wires of 2 

mm

2

).

Backlight luminance

To prevent varying luminance among backlights when using 
multiple backlight types, please use the same backlight 
power supply.

Terminal connection

Tighten the terminal screws with a torque of 0.8 N·m or 
less.

Free voltage input type

How to reset multiple panel mounting type counters all 

at once (input is the same for count)

• Use start input terminals   and   for free voltage input

and reset input terminals   and   for non-voltage input.

Be aware that the application of voltage that exceeds the

voltage range of the H level to the start input terminal,
and the application of voltage to the reset input terminal,
can cause damage to the internal elements.

Since the current flow is very small from reset input

terminal  , please use relays and switches with high
contact reliability.

• When inputting a reset with an open collector of a

transistor, use a transistor for small signals in which I

CBO

is 1 μA or less and always input with no voltage.

To reset externally, short reset input terminals 

 and

on the rear.

• Input uses a high impedance circuit; therefore, erroneous

operation may occur if the influence of induction voltage

is present. If you plan to use wiring for the input signal
that is 10 m 

32.808 ft

. or longer (wire capacitance 120

pF/m at normal temperature), we recommend the use of

a CR filter or the connection of a bleeder resistor.

PC board mounting type

For both panel mounting and PC board mounting types

Non-voltage input type

Voltage input type

For external power supply use manganese dioxide or

lithium batteries (CR type: 3 V).

Always reset after external power is applied and confirm

that the display reads “0”.

• Make the wiring from the battery to the hour meter unit as

short as absolutely possible. Also, be careful of polarity.

• Calculate battery life with the following formula.

t = A/I
t: battery life [h]
I: LH2H current consumption [mA]
A: battery capacity until minimum

operation voltage is reached [mAh]

• Hand solder to the lead terminal. Do not dip solder. With

the tip of the soldering iron at 300 °C 

572 °F

 perform

soldering within 3 seconds (for 30 to 60 W soldering iron).

Notes: 1) Use the following as a guide for choosing transistors used for 

input (Tr). 

Leakage current < 1 μA

2) Use as small a diode (D) as possible in the forward voltage so

that the voltage between terminals 3 and 4 during reset input

meets the standard value (0.5 V). (At IF = 20 μA, forward

voltage: Max. 0.1 V)

Note: Make sure that H (reset ON) level is at least 4.5 V.

3

or

D

Tr

4

3 4

3 4

D

D

3

or

+V

+V

R

Tr

4

3 4

3 4

3 4

2

2

5

2

Red

Green

5

6

2 6

 

24 V DC

24 V DC

CAUTIONS FOR USE

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