Linktop HC-21 User manual

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 1 of 17
Electronic Stethoscope
(Model: HC-21)
Xiamen Linktop Technology Co., Ltd.
User Manual
(Version: A/0)

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 2 of 17
Foreword
This manual is a part of a medical product - the Electronic Stethoscope.
Linktop bears no liability and provides no guarantee with regard to damage (including indirect
damage) arising due to this user manual not being complied with.
Prior to using the medical product, it is required to read this user manual carefully.
The user manual should be kept in a safe place for the whole duration of using the
medical product.
It should be provided to every subsequent owner or user of this medical product.
It should be updated on the basis of every supplementation received from the product
manufacturer.
The aim of this manual is to describe a medical product – the Electronic Stethoscope – taking
into account the following in particular:
Description of the medical product,
Safety of use,
Maintenance,
Troubleshooting,
Servicing.

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 3 of 17
1. SAFETY GUIDE
Please read the entire instruction manual before you use Electronic Stethoscope. It will give
you a better understanding of how the product works.
1.1 Warnings
Using this medical product is not a substitute for visiting a physician and may not delay
obtaining medical assistance in sudden pathological conditions.
This medical product can be operated by adults only.
Do not perform auscultation with this medical product if there are any wounds or
abrasions within the spot examined.
In the event when the user of this medical product has a pacemaker implanted, the
admissibility of using this medical product should be consulted with a physician.
The device is sensitive to external factors - noises or murmurs may have a negative
impact on the quality of recordings.
This medical product is not intended for diagnostics in emergency conditions! If you
suspect any hazard to life or health (e.g. trouble breathing, impaired consciousness,
significantly increased respiratory rate, panic), do not use this medical product! In such a
situation, contact a doctor urgently.
This medical product includes small elements that can be ingested or aspirated: keep the
product and its accessories away from children.
The power supply cable may constitute a strangulation hazard: any examination of
children should be conducted under supervision.
Only Magnetic USB cable paired with a charger provided by the manufacturer –or a
charger with parameters consistent with those specified in this manual –should be used
for charging the device.
Do not perform examinations with the stethoscope or put it to the body while it is being
charged.
Do not attempt to replace the battery on your own.
Prior to commencing examination, please disconnect the charging cable from the
stethoscope!
In case of noticing any irregularities in functioning of the stethoscope or any damage to it,
stop using it immediately and contact the manufacturer.
Prior to using the stethoscope, make sure that it has no visible damage.
The stethoscope should not be opened or modified.
The stethoscope should not be immersed in water or other liquids.
1.2 Precautions
This medical product is an electronic stethoscope. It should be used solely for recording
the respiratory system or heart auscultation sounds. This medical product does not
analyze the sounds recorded.
A recording made using this medical product may be transmitted only via applications
approved by Linktop. The recordings made using any applications other than those
specified below may not be reliable, which may lead to their content being interpreted

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 4 of 17
incorrectly by a doctor and, in consequence, to incorrect diagnosis. The list of approved
applications is available at the www.linktop.com website.
Do not expose the product to impact of any chemical substances, sunlight, or high
temperature.
Protect the stethoscope against shocks and falls.
The product should be used in ambient temperature from 15 to 40°C.
Do not expose the stethoscope to temperatures greater than 50°C or lower than 0°C.
Do not use the product when the relative humidity exceeds 90%.
In case of noticing any irregularities in functioning of the stethoscope or any damage to it,
stop using it immediately and contact the manufacturer.
The product should be stored in a clean and dry place.
This medical product is not sterile and must not be sterilized.
The stethoscope should be charged only by means of the charging cable included in the
set supplied. In any other case, use a charger that meets the requirements described of
this manual.
When the product is being charged, all its functions, including data transmission, are
blocked.
The stethoscope does not include any parts that can be replaced by the user on their
own.
If you experience any skin irritation or redness after use this device, please stop using the
device.
1.3 Contraindications
N/A
1.4 Adverse Reactions
N/A
1.5 Special Population
N/A
1.6 Intended Use/Indications for Use
The Electronic Stethoscope is intended for the detection, amplification and recording of
sounds from the heart, lungs, anterior and posterior chest with selective frequency ranges. It
can be used on any person undergoing a physical examination.
2. DEVICE DESCRIPTION
2.1 General Description
Electronic stethoscope's proprietary environmental noise cancellation technology can help you
hear the human body's important heart and lung sounds. This technology can reduce
background noise by an average of 85%, but will not filter out important auscultation sounds.
Electronic stethoscope is compatible with both headset auscultation and Bluetooth recording
auscultation, which is convenient for doctors in clinical diagnosis or remote auscultation. The

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 5 of 17
excellent acoustic sensitivity and high-quality sound transmission of this product provide
reliable performance and comfortable experience for medical professionals who are
committed to achieving the best patient care.
2.2 Device Drawing
Figure 1. Device Drawing
2.3 Device Components
The main elements of the stethoscope are presented on Figure 2.
Figure 2. Device Components
Description of each component
①
Power button: Power on/off and Bluetooth pairing Button.
②
Indicator light: Two color LEDs
③
PC socket: 3.5 mm mini jack socket – used for connecting PC or Mobile phone to
record
④
Charge port: Magnetic USB interface – used for charging
⑤
Headphones socket: 3.5 mm mini jack socket – used for connecting headphones
⑥
Membrane
⑦
Audio jack silicone plug – used for waterproof and dustproof of the audio jack.
The table below includes the description of the Button and LEDs on the stethoscope:
In the shutdown state, Long press the button 3 seconds to turn on
In the power-on state, Long press the button 3 seconds to power off

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 6 of 17
In the working mode, short press the button to enter sleep mode
In the working mode, double press the button to switch auscultation mode
(heart sound auscultation and lung sound auscultation mode)
Green light is always on in lung sound auscultation mode when Bluetooth
connected
Green light flashes slowly when charging
Green light is always on when fully charged
Blue light is always on in heart sound auscultation mode when Bluetooth
connected
2.4 Specifications
Product Name
Electronic Stethoscope
Model
HC-21
Power supply
5V DC 500mA (lithium-ion battery)
Dimensions
Height 1.02 inches (26mm)
Base diameter 1.77 inches (45 mm)
Membrane diameter 1.7 inches (43.8 mm)
Weight
62g
Battery life
More than 500 charging cycles
Frequency range
RF: ISM, 2.402-2.480GHz
Attenuation
100Hz-500Hz ≤ 12dB
600Hz-1000Hz ≤ 20dB
Modulation
GFSK
RF power
4.5 dBm
Bluetooth version
Bluetooth 5.0
Type of application
parts applied
BF
Protection class
IP22
3. USING INSTRUCTIONS
3.1 Preparations for use
3.1.1 Application
Prior to using the stethoscope, it is necessary to confirm whether your mobile phone is
supported by stethoscope. The available mobile phones are as follows:
(1) Mobile phone or tablet with Android 7.0 or higher and Bluetooth 4.2,
(2) iPhone that supports Bluetooth 4.2, such as: iPhone 7 / 7 Plus / 8 / 8 Plus / X / XR / Xs /
Xs Max / 11 pro / 11 pro Max / 12 mini / 12 / 12 pro / 12 pro Max.
Note: Always use the most recent version of the application ("NexStetho" application). You
can download it from Official website: https://www.linktop.com, Google Play or App Store.

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 7 of 17
3.1.2 Electronic Stethoscope
(1) When using the stethoscope for the first time, long press the power button 3 seconds
to power on.
(2) If the battery of the device is low, it will not be able to start up. Connect the magnetic
cable included in the set to the charging interface of the stethoscope to charge it
(Figure 3) and remove it after it is fully charged.
Figure 3. Charging demo
Note: When the battery of the stethoscope is charged, the green LED is flashing, When the
green LED is always on, means fully charged, you can disconnect the cable.
(3) In order to charge the stethoscope, it is necessary to connect it to a charger using
only the cable provided. In any other case the cable should be connected to a
charger that meets the requirements described in this manual. After connecting the
stethoscope to the charger, it should be left until fully charged (when the charging
LED is always on).
Note: When the stethoscope is being charged, all its function is blocked.
3.1.3 Activities during operation
The stethoscope can be used in one of the three modes listed below:
1Use the application to connect with Electronic Stethoscope via Bluetooth.
2Use the application to connect with Electronic Stethoscope via 3.5mm audio cable.
3Use headphones to connect stethoscope for auscultation.
When recording, make sure that the jack socket is not covered and do not knock on the
casing. After putting the stethoscope to the body, click [Start] button to start recording on the
application, and the application will show information on the recording progress.
1. Patient auscultation mode using the application to connect with Electronic
Stethoscope via Bluetooth
(1) Use an Android phone to download the "NexStetho" application from Google Play or

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 8 of 17
use an iPhone to download the "NexStetho" application from the APP Store.
(2) Please make sure that the Bluetooth of the mobile phone is open, and the
stethoscope is turned on.
(3) Launch the "NexStetho" application, click "Add Device", the application will search for
the Bluetooth of the stethoscope until it finds a device with the Bluetooth name
"HC-21", select and connect, the application will automatically bind the stethoscope.
(4) Use the application to select the auscultation mode and confirm whether to use the
heart sound auscultation or lung sound auscultation mode.
The heart sound auscultation mode is suitable for low-frequency sounds in
auscultation, such as the first heart sound, the second heart sound, the rumbling
diastolic murmur of mitral valve stenosis, etc. When using it, touch the body surface
to be checked lightly, but care should be taken to avoid body parts and Additional
sound caused by skin friction.
The lung sound auscultation mode is suitable for high-pitched sounds in auscultation,
such as murmurs of aortic regurgitation, breathing sounds, bowel sounds, etc. When
using it, touch the body surface to be inspected tightly.
(5) Select the auscultation site and confirm whether to auscultate the lung or the heart.
(6) Putting the stethoscope membrane (Figure 4) to the patient’s body at specific spots
indicated by the doctor, and holding it at each spot, click the start button in the
application to record until the auscultation time is sufficient, click the stop button to
end the recording.
Figure 4
(7) It is recommended to record sound at all the spots indicated by the doctor.
(8) If you hear that the quality of sound recorded at some spots is poor, it is necessary to
repeat recording at those spots.
2. Patient auscultation mode using the application to connect with Electronic
Stethoscope via 3.5mm audio cable

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 9 of 17
It is necessary to launch the Recording application, connect the stethoscope via 3.5mm mini
jack cable.
The stethoscope only supports connecting with Windows PC, and only supports
recording APP: Voice Recorder.
(1) Select the auscultation site and confirm whether to auscultate the lung or the heart.
(2) Putting the stethoscope membrane (Figure 5) to the patient’s body at specific spots
indicated by the doctor, and holding it at each spot, click the start button in the
application to record until the auscultation time is sufficient, click the stop button to
end the recording.
Figure 5
(3) It is recommended to record sound at all the spots indicated by the doctor.
(4) If you hear that the quality of sound recorded at some spots is poor, it is necessary to
repeat recording at those spots.
3. Patient auscultation mode using headphones to connect Electronic Stethoscope
In this mode, no need to connect the application, it needs to connect headphones to the 3.5
mm mini jack socket.
The stethoscope LED will show a blue flashing indicator that the heart auscultation filter is
active. After double pressing the stethoscope button, the filter will be switched to the lung
auscultation mode, the stethoscope LED will show a green flashing indicator.
Although it is possible to use various type of headphones, in view of the range of
frequencies present in auscultation sound signals and levels thereof it is recommended to

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 10 of 17
use headphones with minimum impedance of 16 Ohm and bandwidth of at least 20 – 20KHz
during auscultation.
3.1.4 Turning the stethoscope off
If you do not use the stethoscope, you can press the stethoscope button to put it into sleep
mode. It is not necessary to turn it off after each use.
If it is necessary to turn off the stethoscope completely, it can be done by pressing and
holding the stethoscope button for 3 seconds. To turn on the stethoscope again, it is enough
to press and hold the stethoscope button for 3 seconds.
Note: If the stethoscope is not turned off when it is not in use, the stethoscope may run out of
battery power.
4. CLEANING AND MAINTENANCE
The stethoscope should be disinfected after each use. It should be disinfected using a cotton
pad or swab moistened with non-alcoholic disinfectant intended for medical products.
• Please take care not to flood the 3.5 mm jack socket with the disinfectant.
• Do not immerse the stethoscope in water or other cleaning liquids and do not clean it under
running water.
• Make sure that the water does not reach the inside of the stethoscope.
5. STORAGE, TRANSPORT AND OPERATION CONDITIONS
5.1 Storage and transport conditions:
Temperature: -20°C do 60°C
Relative humidity: 10% do 95%
Atmospheric pressure: 700 hPa ~1060 hPa
5.2 Operation conditions:
Temperature: 5°C to 40°C
Relative humidity: from 10% to 95%
Atmospheric pressure: 700 hPa ~1060 hPa
6. TROUBLE SHOOTING
Malfunctions
Reason
Solution
APP cannot connect to
the device via
Bluetooth
Bluetooth is not in
pairing state
The device enters sleep mode, short press the
button to enter working mode.
The device is turned off, long press the button
for 3 seconds to turn on the device.
Incomplete sound
transmission via
Bluetooth
Wrong connection
distance
Keep the distance between the app and the
device within 2 meters
Bluetooth version is
low
Must use Bluetooth 4.2 or higher mobile phone
or tablet

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 11 of 17
Serious recording
noise
Noise caused by skin
friction
Touch the body surface to be checked lightly,
but care should be taken to avoid body parts
and Additional sound caused by skin friction.
7. SERVICING
In case of noticing any irregularities in functioning of the medical product, contact the
maintenance service at the e-mail address: [e-mail]
Linktop bears no liability and provides no guarantee with regard to damage (including indirect
damage) arising due to this user manual not being complied with.
8. WARRANTY
The warranty-related information regarding warranty duration, its scope, its territorial range,
and the rights in case of finding a defect are described in detail at the address:
www.linktop.com .
Note: The device and accessories out of shelf life or use life should not be thrown randomly
and should be recycled by the manufacturer.
To dispose of packing materials, take appropriate actions in accordance with the rules and
regulations in force in your area to prevent adverse ecological effects.
9. PACKAGE CONTENTS
(1) Electronic Stethoscope × 1
(2) User manual × 1
(3) Magnetic USB charging cable × 1
(4) Audio jack silicone plug x 2
10. LABEL SYMBOLS
1.
Symbol for "MANUFACTURER". This symbol shall be
accompanied by the name and the address of the manufacturer.
2.
Serial number
3.
DATE OF MANUFACTURE. This symbol shall be accompanied by
a date to indicate the date of manufacture.
4.
Symbol for "AUTHORISED REPRESENTATIVE IN THE
EUROPEAN COMMUNITY". This symbol shall be accompanied
by the name and the address of the authorized representative in
the European Community, adjacent to the symbol.
5.
Collect separately from other household waste
6.
IP classification

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 12 of 17
7.
Refer to user manual
8.
Type BF Applied Part
9.
Symbol for “ATTENTION”
Caution! Follow operating instructions!
Failure to do so could place the patient or operator at risk.
10.
Conformity indication with the essential health and safety
requirements set out in European Directives.
11.
Atmospheric pressure limitation
12.
Batch code
13.
Catalogue number
14.
℃
40
℃
5
Temperature limit
15.
Keep away from sunlight
16.
Keep away from rain
17.
Do not use if package is damaged
18.
Class II equipment
19.
Humidity limitation
20.
Fragile; handle with care
21.
Use by date
22.
Symbol for "IMPORTER". This symbol shall be accompanied by
the name and the address of the importer, adjacent to the symbol.

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 13 of 17
11. ELECTROMAGNETIC COMPATIBILITY
The Electronic Stethoscope has been tested and found to comply with the electromagnetic
compatibility (EMC) limits for medical devices. These limits are designed to provide
reasonable protection against harmful interference in a typical medical installation.
a) Do not use a mobile phone or other devices that emit electromagnetic fields, near the unit.
This may result in abnormal operation of the unit.
b) Caution: This unit has been thoroughly tested and inspected to assure proper performance
and operation!
c) Caution: this machine should not be used adjacent to or stacked with other equipment and
that if adjacent or stacked use is necessary, this machine should be observed to verify normal
operation in the configuration in which it will be used.
Manufacturer’s declaration – electromagnetic emissions
The Electronic Stethoscope is intended for use in the electromagnetic environments specified
below. The customer or the user of the Electronic Stethoscope should assure that it is used in
such an environment.
Emissions test
Compliance
Electromagnetic environment - guidance
RF emissions
CISPR 11
Group 1
The Electronic Stethoscope use RF energy only for
its internal function. Therefore, its RF emissions are
very low and are not likely to cause any
interference in nearby electronic equipment.
RF emissions
CISPR 11
Class B
The Electronic Stethoscope is suitable for use in all
establishments, including domestic establishments
and those directly connected to the public
low-voltage power supply network that supplies
buildings used for domestic purposes.
Harmonic emissions
IEC 61000-3-2
Not applicable
Voltage function /
flicker emissions
IEC 61000-3-3
Not applicable
Manufacturer’s declaration – electromagnetic immunity
The Electronic Stethoscope is intended for use in the electromagnetic environment specified
below. The customer or the user of the Electronic Stethoscope should assure that it is used in
such an environment.
Immunity test
IEC 60601 test level
Compliance level
Electromagnetic
environment -
guidance
Electrostatic
discharge (ESD)
IEC 61000-4-2
±8kV contact
±2, 4, 8, 15kV air
±8kV contact
±2, 4, 8, 15kV air
Floors should be
wood, concrete or
ceramic tile. If floors

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 14 of 17
are covered with
synthetic material,
the relative humidity
should be at least
30%.
Electrostatic transient
/ burst
IEC 61000-4-4
±2kV for power
supply lines
±1kV for input/output
lines
Not applicable
(Battery operated
device)
Mains power quality
should be that of a
typical commercial or
hospital environment.
Surge
IEC 61000-4-5
±1kV differential
mode
±2kV common mode
Not applicable
(Battery operated
device)
Mains power quality
should be that of a
typical commercial or
hospital environment.
Voltage dips, short
interruptions and
voltage variations on
power supply input
lines
IEC 61000-4-11
<5% UT
(>95% dip in UT)
for 0.5 cycle
40% UT
(60% dip in UT)
for 5 cycles
70% UT
(30% dip in UT)
for 25 cycles
<5% UT
(>95% d i p in UT)
for 5 sec
Not applicable
(Battery operated
device)
Mains power quality
should be that of a
typical commercial or
hospital environment.
If the user of the
Electronic
Stethoscope requires
continued operation
during power mains
interruptions, it is
recommended that
the Electronic
Stethoscope be
powered from an
uninterruptible power
supply or a battery.
Power frequency
(50/60 Hz) magnetic
field
IEC 61000-4-8
30 A/m
30 A/m
Power frequency
magnetic fields
should be at levels
characteristic of a
typical location in a
typical commercial or
hospital environment.
NOTE UTis the a.c. mains voltage prior to application of the test level.
Manufacturer’s declaration – electromagnetic
The Electronic Stethoscope is intended for use in the electromagnetic environment specified
below. The customer or the user of the Electronic Stethoscope should assure that it is used in
such an environment.
Immunity test
IEC 60601
test level
Compliance
level
Electromagnetic environment - guidance

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 15 of 17
Conducted RF
IEC 61000-4-6
3Vrms
150kHz to
80MHz
Not
applicable
(Battery
operated
device)
Portable and mobile RF communications
equipment should be used no closer to
any part of the Electronic Stethoscope,
including cables, than the recommended
separation distance calculated from the
equation application to the frequency of
the transmitter.
Recommended separation distance
Radiated RF
IEC 61000-4-3
10V/m
80MHz to
2.7GHz
10V/m
Where pis the maximum output power
rating of the transmitter in watts(W)
according to the transmitter
manufacturer and dis the recommended
separation distance in meter (m)
Field strengths form fixed RF
transmitters, as determined by an
electromagnetic site survey, ashould be
less than the compliance level in each
frequency range. b
Interference may occur in the vicinity of
equipment marked with the following
symbol:
NOTE 1 At 80 MHz and 800 MHz, the higher frequency range applies.
NOTE 2 These guidelines may not apply in all situations. Electromagnetic is affected by
absorption and reflection from structures, objects and people.
aField strengths from transmitters, such as base stations for radio (cellular/cordless)
telephones and land mobile radios, amateur radio, AM and FM radio broadcast and TV
broadcast cannot be predicted theoretically with accuracy. To assess the electromagnetic
environment due to fixed RF transmitters, an electromagnetic site survey should be
considered. If the measured filed strength in the location in which the Electronic Stethoscope

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 16 of 17
is used exceeds the applicable RF compliance level above. The Electronic Stethoscope
should be observed to verify normal operation. If abnormal performance is observed,
additional measures may be necessary, such as reorienting or relocating the Electronic
Stethoscope.
bOver the frequency range 150kHz to 80 MHz, filed strengths should be less than 3V/m.
Recommended separation distances between portable and mobile
Test
Frequency
(MHz)
Band
(MHz)
Service
Modulation
Maximum
Power (W)
Distance
(m)
Immunity
Test Level
(V/m)
385
380-390
TETRA 400
Pulse modulation 18 Hz
1.8
0.3
27
450
430-470
GMRS
460, FRS
460
FM ±5 KHz
deviation 1KHz sine
2
0.3
28
710
704-787
LTE 13, 17
Band
Pulse modulation 217
Hz
0.2
0.3
9
745
780
810
800-960
GSM
800/9 00,
TETRA
800 ,
iDEN 820,
CDMA
850, LTE 5
Band
Pulse modulation 18 Hz
2
0.3
28
870
930
1720
1700-1990
GSM 1800 ,
Pulse modulation 217
2
0.3
28

File No.: QR-HC21-C-C09
Xiamen Linktop Technology Co., Ltd.
Page 17 of 17
C D M A
1 9 0 0 ,
GSM 1900,
DECT,
LTE 1, 3,
4 , 25
Band,
UMTS
Hz
1845
1970
2450
2400-2570
Bluetooth,
WLAN
802.1 1
b/g/n, RFID
2450, LTE 7
Band
Pulse modulation 217
Hz
2
0.3
28
5240
5100-5800
WLAN
802.11 a/n
Pulse modulation 217
Hz
0.2
0.3
9
5500
5785
12. Statement
Hereby, Xiamen Linktop Technology Co., Ltd., declares that this Electronic Stethoscope is in
compliance with the essential requirements and other relevant provisions of Directive
2014/53/EU.
The full test of the EU declaration of conformity is available at the following internet
address: www.linktop.com
Xiamen Linktop Technology Co., Ltd.
Address: Room 501-2,502,503, North Building, Torch Hi-Tech Zone, No.56-58 Huoju
Road, Xiamen, 361000, Fujian, P.R. China.
Website: www.linktop.com