Remember early 2000s, when the first iPod came out? Everyone was wowed by how a $200 MP3 player was able to 1000 songs right in your pocket! Gone were the days of the cassette tape and CDs… or so we thought. Well now, we’re bringing it back retro-style! Imagine having the same MP3 player power where you can fit a thousand songs, in your… CASSETTE TAPE! Yes, use any standard SD card of any size and load your very own mixes into your cassette tapes. If you’re feeling adventurous, you can even power your MP3 player with the power of the sun!
The goal of this project is to retrofit a cassette tape with a modern MP3 player so that you can jazz out in old school fashion. Yes, we know you probably have an iPhone, or an iPad, or an iPod or some other iPlayer. The point of this project is to remember the old times – where we were all rockin’ cassette tape players as we jogged and went to school. For those of you who don’t remember the old times (or weren’t even born), you can just imagine, and really realize how lucky you all are! 😛
This is not the most difficult project in terms of engineering. You should be able to get it working without a problem because there isn’t much solder connections. On the other side, it is fairly technically difficult in terms of the small parts. The magnet wire will probably give you the biggest challenge because it’s small, and can be quite tedious. If you’re a soldering noobie, I recommend getting some help – from a friend, or a parent, etc. Also, use masking tape to hold things down. It’ll make this project 10x easier!
Here are the items you’ll need:
Tools you will need
- Soldering Iron with Solder
- Hot Glue
- Small +/- Screwdrivers
- MicroSD Card
- Mini USB Cable
Tools that will help
- Masking tape
- Helping Hands
Cassette Tape MP3
- 1x Mini MP3 Player
- 5 x Momentary Switch
- 6′ 30 AWG Magnet Wire
- 1 x Cassette Tape
- 1x Solar Panel
- 1N4148 Diode
- Double-sided Foam Tape
0) Test the MP3 player
– Grab a Micro SD card and put it into the MP3 player. Some cards over 4GB might not work so try to use something 4GB or below.
– Connect to your computer via mini-USB cable. A prompt should pop up on your computer, and it should be recognized as a disk.
– Load some MP3s
– Connect a pair of speakers or headphones and play them
– If the computer doesn’t recognize the MP3 player, try loading songs onto the Micro SD card manually, then try to play the songs on the MP3 player.
1) Take apart the mini-MP3 player
First, use a flathead screw to pop the MP3 player open. Be gentle and careful. If you are too rough, you may end up breaking things in there.
If you start from the top layer, you’ll be able to peel the reflective layer off first. That may make it easier for you to take apart. When you get to the inside, you’ll see that the switch and the USB jack are protruding a bit outside. You just have to gently pry between to get the circuit board and the battery out.
Here’s what it looks like when you’ve taken all the parts apart. You’ll get the two parts of the shell, a plastic switch and the battery and the circuit board (connected). You can recycle or throw the plastic parts away, or save them for other projects.
2) Cut or desolder the audio jack
Depending on what your experience is with soldering, this may be challenging. This step can be done in one of three ways.
The first way uses the least amount of tools. You can simply use a diagonal cutter and cut the 3 parts of the foot of the audio jack that’s soldered to the circuit board. It should be able to come apart pretty easily. Just be weary to not force it out too strong, or else the metallic pads (needed to connect the jack to the circuit board) might come out. If that happens, you will have a very hard time trying to reconnect it.
The second way uses tweezers and a soldering iron. You will have to slowly pry one leg up while using a soldering iron to desolder that same leg. Then move on to the next leg, and the next leg. Then go back to the first leg, rinse-and-repeat. Keep doing it until all of them comes apart.
A third way, which is arguably the easiest way, requires a soldering rework station. But if you have a soldering rework station (which is used to take surface mounted or other “hard to desolder” parts apart), you should already know how to do this 🙂
Now look for the side of the cassette tape that has the two protrusions in the middle. Use a pair of diagonal cutters to cut the BOTTOM one. Leave the top part alone. We’ll be using it later. If by accident, you skimped the instructions and cut the top part, the world won’t end – don’t worry.
Now try to fit the circuit board inside like so. You’ll see that it won’t fit. Carefully snip the corner of the circuit board just like the picture. As long as you don’t cut into the circuit board where there are lines, you’re fine. It should be able to fit snugly!
5) Prepare the magnet wire
Cut 10 pieces of magnet wire, each about 4 inches. Be careful, because these wires get lost easily – once you’ve dropped them from your chair, our experience is that they disappear into the void! Once you’ve cut them, you’ll see that the magnet wire has a small layer of coating that is protecting it. We have to strip the coating but using a pair of scissors or even a wire cutter is really hard to do.
Next, use a piece of sand paper to sand the insulation off the tiny wires! If you do it right, it should look like a small end of a copper wire should reveal itself after the coating is sand away. This should be roughly 2mm on each end.
6) Wire the momentary switches to MP3 player
We’ll be using these momentary switches to turn the MP3 players on and off, instead of using the onboard “touch” buttons. In order for us to do this, you’ll need to wire up the momentary switches with the magnet wires.
You will be soldering TWO wires to each switch. It doesn’t matter where you solder the first wire, as long as the second wire is DIAGONAL from the first one.
Do this for all 5 switches. You’ll find that sometimes, the wires will indeed come apart easily. If you’ve done the soldering correctly, you should be able to tug lightly on the wire and the wire should stay on soldered to the switch. If you tug and it comes apart, it probably means you need to resolder again. Sometimes, if the solder is too stubborn, make sure your soldering iron tips is clean of solder before attempting it again.
Leave these momentary switches stuck with the masking tape as it’ll make the next step a little easier.
Now grab the MP3 player circuit board and turn it over. You’ll see a sticker with metal disks that you can peel off. If you look at how this works, you’ll see that the metal disks “connect” the bridge that exists on the buttons of the MP3 player. It’s essentially a switch!
What we’ll do here is replace that “metal disk” action with our momentary switches.
Grab that soldering iron again and first, TIN the 5 buttons of the circuit board. Tinning just means putting soldering on the metal surfaces before you start soldering the wires on. This will make your life a bit easier.
PROTIP: You can also see I use a ton of masking tape to hold things down. This approach for this project is much better than helping hands, or even actual human helping hands!
Then just solder the 5 momentary switches like so. One wire of the momentary switch should go on the outside of a circle. The other goes on the inside. I also recommend using masking tape on the outer edges. I did this because I didn’t want the wire coming from the inside to bridge with the outside of the circle by accident.
Once you’re finished, you can also try a nudge test to see if the wires will come apart from the circuit board. If they do, then it probably needs to get resoldered.
7) Audio jack
Now, SLOWLY turn the circuit board over and wire up the audio jack using the same methods as previous steps to:
– Cut the wire and stripping the ends
– Soldering wires onto the audio jack
– Soldering the audio jack (with wires) onto the board
One thing to note with the audio jack: if the legs of the audio jack broke when you were cutting it in the earlier step, you can just use the other side of it. Soldering onto it is a little harder but the metallic pads will work and will still allow you to transfer audio without any performance loss!
Again, use masking tape to hold things down!
8) Testing time!
Connect all the relevant components:
– Audio to a speaker
– Mini-USB to a power source
– A micro-SD card inside the slot
Turn the device on, and see if it plays. Then check all the buttons. It should be pretty convenient if you’ve left the momentary switches upside down. You just have to press them down a bit. Using this method, you’ll be able to find out two things:
1) Whether the buttons work – if they don’t work, check that particular connection (the solder joints)
2) What each button does – make note of the Rewind/Fast-Forward, VolumeON/VolumeOFF, and the ON/OFF button.
Once you’ve confirmed that they all work, you can move onto the next step.
Carefully load the MP3 circuit board into the cassette tape housing to see if it fits. If it does, use some hot glue to secure it into place. Make sure you don’t use too much hot glue – if it gets too tall, you will not be able to close the cassette tape up!
Now, place the audio jack, and glue it into place. The audio jack is probably the tallest item in the cassette tape so make sure you place it first, then glue the sides into place. If you glue the bottom first, you run the risk of the glue drying and making the audio jack’s height taller than it should be. (but then again, you can use rubbing alcohol to remove some reasonable amount of dried hot glue if you ever mess up!)
This step is probably one of the most tedious parts of this project, next to soldering the magnet wire. You’ll be placing the momentary switches in the housing as in the picture and gluing them into place. Make sure you do a fit test before you start gluing.
For this one, I put the volume on the left side, and the fast-forward / rewind buttons on the right side.
Another neat trick you can do is to cut a little bridge to give some room to nest the wires in place. This will help when you try to put the cover on later – the fit will be more snug.
Don’t worry if your wires don’t look as clean as this picture. This is my second time doing this so I’ve had some time to think about layout. Just try your best to “tame” the wires.
10) Time to load the switch.
Using the first method I used to take the audio jack out, using diagonal cutters, I cut the switch out. You’ll probably ruin the switch (because it’s small and fragile), but you have a replacement one as a part of your kit!
If you don’t feel like taking out the switch that’s on the circuit board, you can also just leave it soldered. It’ll just make the next step a little harder though.
Unlike other kits, you will have to connect all 3 legs on the switch – because the MP3 player is capable of using both the battery and wall power. The pinouts for this are simple. Just match the legs of the switch to the pads exactly. Left to left. Middle to middle. And right to right.
Then cut a portion of the cassette tape holder on the top right hand corner and glue everything in place.
11) Load the battery and test!
NOTE: If you are connecting a solar circuit here, move onto to the SOLAR CIRCUIT section and skip this step. Then come back to step 12 once you’re done.
Time to solder the battery back on. To make it fit, you’ll have to cut the bottom left hand part of the cassette tape housing a bit. Then you’ll have to take the tape off the battery a bit and carefully fold it from the top down (see picture). This will make the battery more snug.
When handling the battery, make sure you’re careful to not puncture anything. Batteries can be dangerous if they are not handled carefully!
Then solder it in place. Red is on the top, black is on the bottom. Then you can tape the battery. Use tape for the battery because it’ll allow you to swap it out for bigger batteries later if you want to (or to put a solar charging circuit!)
After all that’s done, you can run a test 1 more time to make sure everything works just the way it’s intended.
Put the cassette tape wheels back into place. You will have to carefully cut them to ensure that they fit.
Mirror and cut the other side of the cassette tape housing so it can fit over the audio jack, micro SD slot and the USB port.
Screw everything back into place.
Decorate it with a label (you can find a template in the resources section.
13) Jam out!
Load your favorite songs and show it off to your friends!
1) Solar Panel & Diode
What you’ll need for this is a solar panel and diode. You’ll also need a pair of wires. You can use the red and black wire that comes with the solar panel, or if you have some of the magnet wire left over, you can use that too. The magnet wire will make your setup a little cleaner.
2) Solder the wire onto the solar panel
Red goes to + and black goes to -. The wires in this picture are pretty long. In reality, you don’t need them to be this long. A good 4 inches will more than suffice.
3) Solder the diode onto the red wire
First, cut the diode so it becomes shorter. Then solder it to the red wire. Make sure the black stripe is AWAY from the solar panel. The point of the diode is to let current flow from the solar panel into the battery but stop the battery from sending power into the solar panel (why on earth would anyone want to power a solar panel!?).
4) Solder the solar panel into the circuit
5) Close up everything
Screw everything on, and then put the labels (see step 12 of the previous instructions). These decorations will make your project look more polished and eye-catching!
Note that the wires in here were too long, so we end up trimming the wires later.
6) Secure solar panel into place
Use the double-sided foam tape to secure the solar panel in place. And off you go! Carry this mix tape around with your favorite songs, and it’ll never run out of power (as long as it gets plenty of sun of course!)
For the template to customize your own cassette tape label, grab the DIY Cassette Tape Template.
This is the retro pattern that we used. You can also right click and download.