The reed switches are available in two types, i.e., a
reed switch having ruthenium-plated contacts and a
reed switch having rhodium-plated contacts.
Please choose the optimum reed switch best-suited
to your intended applications from a wide selection
of reed switches.
Features
●
Compact and Lightweight
The reed switches are suitable for use as a com-
pact and lightweight magnetically responsive switch,
thereby rendering equipment smaller.
●
Ambient Resistance
Contacts of the reed switch are encapsulated in a
glass tube together with inert gas (nitrogen gas),
which protects the reed switch from the effects of
the exterior environment, for example, gas, dust,
or moisture in the atmosphere.
●
Relatively stable characteristics are ensured from
low to high temperatures. The reed switches are
usable over a wide variety of temperatures.
●
High Reliability
Considerably high reliability is assured as a result
of the adoption of NEC TOKIN’s unique contact
processing technique.
●
High-speed Operation
Since the reed switch operates at high speed, it is
easy to interface with a transistor or an IC.
●
Long Life
A long-life reed switch without mechanical friction
is implemented as a result of its simple structure.
●
Extensive Applications
When used in combination with a permanent magnet,
the reed switch finds extensive application in switching
and sensing.
4 Reed Switches Applications Vol.04
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
2007.08.03 P0841RSAP16VOL04E
Structure and Principle of
Operation
A reed switch encapsulated in a glass tube has two
ferromagnetic reeds which face each other with a
given contact clearance between them, as shown in
diagrams on the right. The glass tube is filled with
nitrogen gas to prevent the activation of the con-
tacts, thus providing improved reliability and ex-
tended life.
Upon receipt of a magnetic field from the outside in
the axial direction of the reed switch, the reeds of
the reed switch are magnetized. The free opposite
ends of the reeds attract each other and come into
contact with each other, to close the circuit. When
the magnetic field is removed, the circuit opens by
means of the resiliency of the reeds.
Ferromagnetic
Reed
Contact
●
Operating Principle of Reed Switch
Glass Tube
S
S
N
N
S
N
Contact Material
●
Ruthenium (Ru) plated contact
Ruthenium-plated contacts developed by NEC
TOKIN’s unique technique are made of a very
hard material having with a high melting point.
The contacts are resistant to mechanical friction
and heat generation, and they have excellent anti-
sticking performance.
●
Rhodium (Rh) plated contact
Power reed switches what are susceptible to rela-
tively large consumption employ Rh-plated contacts,
which results in extended life of the reed switches
(compensating for contact consumption).
Characteristics of Contact Material
Items
Atomic Weight
Melting Point (K)
Boiling Point (K)
Density (g/cm )
Specific Heat
(J/g•K) 0°C
Hardness (HV)
Tensile Strength
(kgf/mm
2
) (N/m
2
)
3
Ru
Rh
(Ruthenium) (Rhodium)
101
2,523
4,173
12.1
0.234
220
50.0
490×10
6
103
2,233
4,000
12.4
0.238
100
54.9
538×10
6
Au
(Gold)
197
1,338
2,983
19.3
0.128
25
13.5
132×10
6
Types and Applications
When used in combination with a permanent magnet,
the reed switch finds extensive applications in which
it provides switching and sensing capabilities.
●
Construction of Reed Switch
Type
Part No.
RD-7AA/
7B/24B
NRS-771
RD-24E
RD-8N
RD-9A/9B
RD-18A/18B
/75AA
NRS-701
Applications
For general control purposes
(about 10W)
Heavy load (50W)
Direct switching of a 3.4W
lamp (for surge current use)
For general control purposes
(about 5W)
Cellular
Notebook
computer
Laundry
machines
Rice
cookers
Toys
Humidifiers Electronic
sewing
machines
Crime
prevention
doors
Electronic
balances
Electrical
Hot-water
equipment supplying
for
apparatus
automobiles
Fan heater VTR
General purpose
High power
Lamp load
Compact
Ultra compact
Light load
Refrigera-
tors
Printers
Copiers
Vending
machines
Flow
meters
Reed Switches Applications Vol.04 5
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
2007.08.03 P0841RSAP16VOL04E
Reed Switches
(The switches are arranged in ascending order of glass tube length.)
*Pre-soldering on terminals are lead-free (Sn100%)
6 Reed Switches Applications Vol.04
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
2007.08.03 P0841RSAP16VOL04E
RD-7AA
φ
2.2max.
RD-7B
φ
2.2max.
RD-8N
φ
2.7max.
RD-24B
RD-24E
φ
2.7max.
Remarks
56.6 ± 0.3
56.7 ± 0.3
57.0 ± 0.3
φ
0.52
φ
0.52
Terminal
dimension is
measured before it
is pro-cessed
(soldered).
14.0max.
57.0 ± 0.3
14.0max.
φ
0.6
17.0max.
10 to 40
5
0.5
0.05
0.5
10
100
0.5
1.0
150
10 to 40
5
0.5
0.05
0.5
10
100
0.5
1.0
150
30 to 50
10
1.0
0.05
0.5
10
(rush current 30)
100
Rush current
of 3A
2.0
150
20 to 60
8
1.0
0.1
0.5
15
100
0.5
1.0
150
21.5max.
φ
0.6
20 to 60
8
1.0
0.05
0.5
50
125V.AC
200V.DC
1.0
2.0
150
With use of
NEC TOKIN’s
standard coil
With use of
four-terminalfall-of-
potential method
Leakage
current of less
than 1mA
200
200
250
10
9
(at an application of 100V.DC)
Faulty operation 98 (fracture 490)
–40 to +125
300
300
4.8
4.9
4.3
1×10
8
5×10
7
5×10
4
12V.DC,
3.4W Lamp load
Rh (Rhodium)
Lamp load use
2.2
2.2
Rh (Rhodium)
Compact, and
general-purpose
use
–
Ru (Ruthenium)
Compact, and
general-purpose
use
N-103
–
Ru (Ruthenium)
Long life
(light load)
1×10
6
50V. DC 0.1A
Resistive load
Rh (Rhodium)
High power
N-102
–
–
–
Numbering System
RD-7B-1020 F
Series
Lead free
Pick up Ampereturn: 10 to 20A
Reed Switches Applications Vol.04 7
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
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