This project was inspired by one of my favourite YouTube channels.

I mention them in my first video for this project where I was prototyping the project Tim's DFPlayer Plus [Talking about it]

The video above is me showing the completed version on the PCB I got from

What does it do?

This board is based around the DFPlayer Mini Module.

This bord can be used in two ways:

1. As an MP3 Player. You can attach speakers and play your music using the two amplifiers.
2. Use it as a tool when diagnosing amplifiers. It will play samples and give a synchronized pulse, to which you can attach your oscilloscope.

The DFPlayer Module only has a mono Amplifier for one speaker.

• There is a mod to do to the DFPlayer module, so that an extra amplifier can be used to give you amplified stereo to two speakers.
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Additions to the DFPlayer Module.

• Another Amplifier to give amplified stereo.
• An Encoder switch to select MP3 File Number and set Volume.
• An OLED to display MP3 File Number or volume.
• 3mm Audio jacks for easy connection of devices.
• Pins for using a 5 volt battery.
• USB Mini socket for powering from USB.
• Buttons for various functions.

Supplies

I will show the main components used in this project.

• Some like the DFPlayer Mini may need to be sourced by yourselves.

Here I have shown the major components.

• One PCB, I have done a shared Project at
• When you order a PCB from you are able to choose just the PCB, or have some or all the components fitted.

One DFPlayer Mini

• There are some bad versions of this be aware of what you find.

One OLED

• This is an 0.96" SSD1306 128x64 I2C module.
• Looking om top of the header pins. the sequence should go GND, VCC, SCL, SDA.

One Rotary Encoder

• This is an encoder with a push button, it has 5 pins.
• I have used a 15mm long shaft with the star serrations.

One STM8S103F3P6

• Make sure it is the "F3" 8k flash, I have used all available flash.

One LM4871 Amplifier.

• I have specified the LM4871, because that is what I have used and it works OK.
• I think the DFPlayer module uses an 8002. But I recommend stick with what I used because mine works.

One AMS1117-3.3

• I am running the system at 3.3 Volts.

Three 3mm Stereo Jacks

• I have attached a data sheet that shows the footprint of the one I have used.

Five Buttons

• 6mm x 6mm, 5mm High

One USB Mini Jack

• I have attached a data sheet for the type I have used.

There are some DuPont headers and pins.

• Note the ones I have for the horizontal pins are the ones that sit flat to the PCB. It should not matter if you use the other type.

All the SMD peripheral components are 2012 Metric, 0805 Imperial size.

• I don't go smaller than this, because I don't see well these days haha.

Tools

I have used an STM8S103F3P6 Microcontroller.

• This will require programming.
• To do the programming an ST-Link v2 is required.
• Also ST Visual Develop IDE from STMicroelectronics.
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Battery Powered Mod

To make it battery powered you will need:

One Li-Po Battery.

• As shown in the image. (Take the size as max size that will fit in the box.)

One USB Battery charger.

• I have used the HW-107, It has the battery protection also.

One Boost.

• I have used an MT3608 based boost, I am boosting the battery voltage to simplify the use of multiple Power options.

One Switch.

• I have used a basic slide switch.

The details of the battery mod can be found at my Instructable.

• The battery mod is made of of the shelf parts/modules.

The Microcontroller Is the STM8S103F3

There are Pads for programming the STM8S103F3

An ST-Link is required.

To programme the STM8S103F3P6 you will need:

• ST Visual Develop IDE from STMicroelectronics.
• ST-Link v2 from shop.

The Circuit

Here is the circuit for those that want to now how it is all wired together.

• The image may not be easy to read so I also attached a pdf.

The project is based around the DFPlayer Mini module.

• Instead of just adding buttons and resistors to make an MP3 Player an OLED Display has been added.
• The OLED Display is there so that specific tracs can be chosen.
• The OLED Display also enables you to set a precise volume level.
• To be able to use a display, a microcontroller is needed to control it.
• I have used an STM8S103F3P6.
• The power comes from a USB supply, but I have also placed an option to power from a 5 volt battery.
• There is a linear regulator to run the system (Vcc) at 3.3 volts.
• There is an extra amplifier added so that we can have two powered speakers and have amplified stereo.
• One should note the the amplifiers used are "Bridge-Mode" (Class a/b) amplifiers, they don't have a common ground.
• Each amplifier should have it's two output pins connected to the terminals of one speaker.

DFPlayer Mod

A Modification is required to get two powered speaker using the Amplifier already on the DFPlayer module and the extra Amplifier we add.

As the The DFPlayer Mini Module stands as bought.

• The two DAC (Digital to Analogue Converter) channels are merged into the one mono amplifier.
• These are merged via Capacitors so they don't interfere with the DAC-L and DAC-R output output pins.
• We need to separate the merge just before the amplifier so that only one channel goes to the amplifier.
• Where we disconnect the merge we need to add a fly-lead which can plug into my PCB.
• This fly-lead will be attached to the second amplifier on the PCB.

I have gone into details on my video here: Tim's DFPlayer Plus [Talking about it]

• If you have a different version of the DFPayer Mini Module, you may want to watch the video to get an idea what heeds doing.
• The circuitry should be the same but the components may be positioned in a different place.
• It will be a matter of tracing both DACs from the large chip to the amplifier.
• Once you find the merge, that's where you need to make the mod. (providing the min chip is stereo)

The Box

I have done another Shared Project to make the box.

• Tim's DFPlayer Plus Box - Share Project - PCBWay