Doctor’s Play Set Portable MP3 Player




Introduction: Doctor’s Play Set Portable MP3 Player

I needed a gift but only had an hour to plan and build it - it also needed to have a medical theme.

I had enough spare parts to build an MP3 player (having ordered two of everything for an earlier cassette tape MP3 player project - based onlonesoulsurfer's classic Instructable and BrittLiv's remix) and a doctor's play set which was surplus to requirement...

This is a very simple project that is suitable for beginners however there are some dangers with LiPo batteries.

  • Double check all connections
  • Ensure there are no shorts
  • Care for the battery properly

Step 1: Tools and Materials


  • Drill
  • Soldering iron
  • Hot glue gun
  • Tin snips
  • Wire strippers
  • Wire cutters
  • Computer (to load MP3 files onto micro SD card)


  • Doctor's play set
  • Cheap earphones
  • Hook-up wire - I only had stranded 26 awg wire available for this build, the larger wires look good with the transparent case but it was a hassle to solder this wire to surface mount solder pads. I would recommend using 22 awg wire if you have it. I would also recommend using different colours to make any trouble shooting regarding connections easier.
  • GPD2846A TF card MP3 decoder board
  • TP4056 with battery protection LiPo Charger Module Board
  • 3.7V 900mah LiPo Battery
  • SPDT switch
  • 3.5mm mono socket
  • 3.5 mm mono plug to 3.5mm stereo socket adapter
  • 3 x momentary buttons
  • USB mini to USB cable
  • 8GB micro SD card
  • Masking tape
  • Lead free solder

Step 2: Prepare the Case

  1. Tape both sides of the case where you plan to drill holes
  2. 3 holes are required for momentary buttons
  3. 1 hole for mono socket
  4. 1 hole for SPDT switch
  5. Rest case on a scrap piece of soft wood and drill small pilot holes
  6. Drill larger holes so the panel mount components will fit
  7. Remove tape
  8. Check the components fit

Step 3: Battery to USB Charger Module

  1. Solder the red (positive) battery wire to B+
  2. Solder the black (ground) battery wire to B-

Step 4: Charger Module to MP3 Module

  1. Solder a wire - In this project I cut the wires much longer than they needed to be - to themiddle tab of the SPDT switch
  2. Solder a wire to one of the side tabs of the SPDT switch
  3. Use heatshrink on connections to switch
  4. Fit switch to case
  5. Ensure switch is in OFF position
  6. Solder the middle wire to OUT + on charger module
  7. Solder the remaining wire to MP3 module BAT +
  8. Solder a wire to charger module OUT - and solder the other end of the wire to MP3 module GND

Step 5: MP3 Module to Mono Socket

  1. Solder a wire to positive tab mono socket
  2. Solder another wire to negative tab mono socket
  3. Use heatshrink on connections
  4. Fix to case
  5. Solder positive wire to SP + on MP3 module
  6. Solder negative wire to SP - on MP3 module

Step 6: MP3 Module to Momentary Buttons

  1. Solder wires to momentary buttons
  2. Use heatshrink
  3. Fix buttons to case
  4. Solder wires to button pads on MP3 modules - I didn’t take a photo of this step with the build but the second picture in this step shows a previous build illustrating how the buttons are connected
  5. In picture 2 orange is for play / pause button
  6. Green is for Volume + and >>|
  7. Yellow is for Volume - and |<<

Step 7: Stethoscope Headphones

  1. Remove chest piece from red stethoscope tubing
  2. Remove red tubing from yellow head set
  3. Remove blue ear pieces from yellow head set
  4. Cut cone shaped plug off chest piece - I used tin snips for this
  5. Drill hole large enough to thread headphone stereo plug and cord through
  6. Put headphone ear pieces in yellow headset where blue ear pieces were
  7. Use hot glue to glue in place
  8. Glue the earphone cables to headset as pictured

Step 8: Load MP3 Files Onto Micro SD Card

  1. Use a computer to load MP3 files onto micro SD card - I used 128 kbps MP3 files to test this player
  2. Insert micro SD card into MP3 module

Step 9: Charge the LiPo Battery

  1. To charge the MP3 player open the case
  2. Plug mini USB into charger module and plug other end to USB port in computer.
  3. Do not leave MP3 player unattended while charging -fire risk.

Step 10: Press Play

  1. Plug headphones into socket
  2. Use a 3.5 mm mono plug to 3.5mm stereo socket adapter to hear MP3 file through both headphones
  3. Turn power on and press play
  4. The other buttons are used to select track (short press) and control volume (long press)
  5. Enjoy the old school 90’s PC quality audio

Step 11: Additional Features

In addition to holding the stethoscope headphones when they are not in use, the case has plenty of extra space for more features:

  1. USB cable storage - I glued a fairy light clip onto the inside of case to hold the cable when it is not in use
  2. Otoscope and tendon hammer storage - I wanted to retain the “Doctor’s Play Set” aesthetic
  3. Warnings - I still had unused space in the case so I added safety info
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    2 years ago

    I've made up a little speaker using the same board, I drilled small holes in the pads for the buttons, making them into through hole connections, I found this made soldering much easier.

    It would have been nice to have had the headphone cable run through the orange tubing that the stethoscope had come with (or maybe a slightly longer one).

    All this little audio boards are great but the hastle is in finding the case for them so I love this


    Reply 2 years ago

    Thanks for the great tip