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Device Overview for the 3M™ Littmann® CORE Digital Stethoscope

Power On/Off

Power On


Depress the power slider to move the switch from the OFF to the ON position. 

The CORE is “ON” when the toggle is flush with the surface of the volume buttons. You will see a white blinking light to indicate that the CORE has been turned ON. You can now hear amplified sounds through the stethoscope. The CORE is also ready to pair with a mobile device and transmit digitized sounds.

Power Off


The CORE is OFF when the toggle is protruding from the surface of the volume buttons. The white light will disappear and you can now hear unamplified sounds through the stethoscope earpieces. 

Standby Mode

The CORE has a 5 minute standby mode to conserve battery life. The white light will disappear when the CORE goes into standby mode and the toggle will remain flat with the surface of the volume buttons (the “ON” position). To power the CORE back ON, push the toggle to the OFF and then the ON position. The white light will appear to indicate the device is ON. 

Adjust the Volume

The CORE’s sound level can be amplified in 7 increments up to 40X amplification over an unamplified, acoustic stethoscope when listening with the stethoscope earpieces. Change the volume level by clicking the plus (+) and minus (-) volume buttons on the side of CORE.

If you are using headphones to listen to the sounds through your mobile device, you will need to adjust your phone’s volume to change the CORE’s volume. 

Note: Changing the volume on the CORE does not affect the volume of a recording on the Eko App running on your mobile device. The recording volume must be adjusted in the App or on the phone itself.

Charge your CORE

When the yellow light starts blinking on the CORE, the battery in the CORE will need to be charged. 

Insert the included micro USB cable into the USB port on the CORE and plug the other (USB-A) end into a UL-certified USB wall charger (max 5 volts). The LED will turn solid yellow, signifying that it is charging. The LED will change to solid green when the device is fully charged.

To fully charge the battery, it should take about 2.5 hours. When fully charged, the CORE should last for about 8 hours of continuous use. We recommend turning the CORE OFF between each use to maximize battery life.

NOTE: The CORE will not turn on while it is plugged in and charging.

Clean your CORE device

The entire CORE stethoscope should be cleaned between patient uses. All cleaning instructions pertaining to the original stethoscope apply.

Under normal conditions it is unnecessary to remove the CORE from the stethoscope tubing for cleaning. All external parts of the hardware can be cleaned with 70% isopropyl alcohol wipes.

NOTE: DO NOT immerse the CORE in any liquid or subject it to any high-pressure/autoclave sterilization processes.

If it becomes necessary to remove the CORE digital attachment from the rest of the stethoscope, pull the stethoscope tubing off of the metal stem of the attachment on both ends of the attachment. You may need to pull firmly to detach the components. Wipe all parts of the stethoscope clean with 70% isopropyl alcohol wipes including the CORE’s surface, stethoscope tubing, tubing connector, and chest piece. Reassemble the stethoscope by reinserting the metal stems into the stethoscope tubing as before.

Ensure the best audio quality

Please follow the steps below to better achieve the highest quality auscultation when using your CORE and stethoscope earpieces:

  1. If possible, perform auscultation in a quiet environment. While the CORE has active noise cancellation, some environmental noise may still be audible during auscultation. 
  2. Use the bell to best listen to low frequency sounds like heart sounds. Use the diaphragm to best listen to high frequency sounds like lung sounds.
  3. Hold the diaphragm firmly against the chest. Avoid any motion. Beware of pressing too tightly, as that can muffle sounds.


LBL 257, Rev B, April 30, 2021

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