Introduction: Altoids Tin Mixer

This project was inspired by mikeasaurus’ really cool wristwatch turntable. I saw it four years ago and promised a friend (that’s you K Mac) I would make her one since her son is a DJ/Rapper. She was also my supplier of
Altoids tins for random projects I would do, so I owed her one. I really did try several times to make the turntable using those audio greeting cards. My kids love buying them for me and I have a collection of the guts in a special
drawer in my workbench. Sometimes when I slam the drawer too hard, Bart Simpson and Homer fight while Bruno Mars sings the Lazy Song. Anyway, I never could quite find the resistor to bypass with the potentiometer. I’m not sure if my eyes are going or the card’s circuits were just shrinking. I thought about making it with an Adruino mini and sound module, but really didn’t want to spend that much money on her. Let’s face it, this will be funny for about 5 minutes and then get tossed on a desk with the other clutter of cube life. That is why the greeting card version is so cool. Luckily, I came across the rather inexpensive ISD1820 module. I noticed in the spec that you could adjust the sample size from 8 seconds to 20 seconds by replacing the jumper and changing
the resistor size. I speculated that adding a potentiometer here would allow me to change the speed of the audio during playback. Sure enough, it worked. Since the sample size is set at the time of recording, I set the potentiometer to 150K when I recorded the music for my “record.” This allowed me to slow down the playback to slow-mo by turning the record in one direction and speed it up Chipmunk style while turning it in the other direction. Unfortunately, there are no scratching sound effects or rewind capabilities. By pushing the play button up and down, you can at least start the song over and emulate a rewind sound. I’m sure there are some other improvements that could be added and leave it to you to post any cool enhancement like I know you will. I was thinking of doing a dual turntable using two modules so you can actually do some mixing, but wanted to stay true to the Altoids tin form factor. I might find a box that can hold a second module for version two and add some lights so G.I. Joe can have a portable DJ booth for Barbie’s disco.

Step 1: Parts

Most of these parts are pretty easy to find online (Amazon, eBay, etc)

If you do not have a good electronics part store or a box of spare parts, you can even find the potentiometer and switch online, but they do cost a bit more since most places want to sell you at least five.

  1. Altoids Tin

  2. ISD1820 Voice Board Sound Recorder Playback Module Onboard MIC

  3. 200K Potentiometer

  4. Momentary SPST NO Push Button Switch

  5. mini speaker from a musical greeting card

  6. AAA battery holder (holds 2 batteries)

  7. 3.5mm audio jack (optional)

  8. Iced tea bottle cap

  9. Self-Adhesive Round Vinyl Pads

  10. Electrical tape

  11. 1/4 inch, 1/8 inch, and 5/8 drill bits

  12. hot glue gun

Step 2: Modifying the Tin

The parts I used all had pretty low clearance, but still, everything just barely fit. If you use different sized buttons or pots, be sure to map out your box first so the electronics fit. I put the speaker in between the switch and pot so make sure you have the right spacing.

The first step of modifying the tin was to drill a hole for the switch. My switch needed a 5/8 inch hole. I added it at the bottom left of the red border. Don't worry if the hole is a little jagged since the switch and its nut will hide your crappy drill job.

Once that is securely in place, I drilled out the two holes needed for the pot. Most pots have a piece sticking up (I'm sure it has an actual name) that holds the pot in place. For the one I used, it needed about a 1/4 inch hole. I placed it just below the "I" in "Altoids" because that was just enough over to the side so the "record" was still within the red border of the tin. Once you have the hole for the pot, line up that little stem piece and mark where that needs to be drilled out. A 1/8 inch hole should work for that. Now screw on the nut and it should be secure.

For this model, I add a 3.5 audio jack so I could plug in a speaker and really pump up the music. The greeting card speaker is not too loud, but acceptable for goofing around. I added a hole on the top left side wall so it would not hit the switch when the lid was closed.

Since the mixer takes two hands to play, I added those adhesive feet to the bottom so it would not slip around while I was mixing. Four feet, one on each corner does the trick.

Finally, you want to put on your "record." I used the lid from a bottle of iced tea, but I've seen the same lid on other types of beverages. Heck, since most people don't even know what vinyl looks like, I'm sure you could use any color. Oh wait, is vinyl making a come back? I can't keep up.

Step 3: The Electronics

First thing you need to do is find a mini speaker. The ones in those musical greeting cards are pretty flat and fit perfectly on the lid of the tin. I just used the speaker's magnet to stick to the lid so no adhesive required.

Before putting the parts in the box, it is easier to wire everything up first. The speaker is easy as you just screw the wires into the green terminals. If you are going to use an audio jack as well, then splice the speaker and audio jack wires together before screwing it into the terminals.

Now I wired up the switch. I used jumper wires so I could just plug the ends into the respective pins. One end of the switch goes to the VCC and the other goes to PLAYL. On this board, the PLAYL plays the song as long as the switch is held down, while the PLAYE button will continue to play until you hit is again. I used the PLAYL button since I wanted to have the option to stop and restart the song at will.

Wiring up the pot is a little tricky since the pins are not labeled well. Basically, you'll see a jumper on the bottom of the board, just above the PLAYL button. It says "P2". Take the jumper out and add the wires from the pot. It doesn't matter which wire you put in which pin, but it does matter which pins on the pot you wire up. Usually you need to use the middle pin and one of the outer pins. You can use an ohm meter to figure out if you have it right.

Last, connect the red (positive) wire from the battery pack to the VCC and the black (negative) to the GND.

The module should work now. You'll want to test it out by holding the "REC" button (red LED will light up) and say something like "Test, test." When you push your button on the tin, it should play back. Congratulations! You are almost there.

Next, I put the AAA battery holder in the far right side. When you buy a battery holder, make sure it is one that does not have a switch. Those are a little too long to fit inside the tin. I placed a piece of electrical tape on the top of the holder since you can see the terminals and I didn't want to take the chance of shorting out the battery on the tin. I used a hot glue gun to secure it in place.

Once the batteries are in place, I moved on to the ISD1820. First I taped up the bottom of the ISD1820 so as not to short it out. A little hot glue on the bottom secures it in place.

The lid should shut. If you are sloppy about your wire size like me, you might have to snake some of the extra wire around the parts so the lid will shut completely. I was able to get mine down completely so I know it does work.

Step 4: Record, Play Back, Scratch.

Finally, you need to find your favorite song (or at least 10 seconds of it) and record it. Don't forget to turn your pot so it is about 150K before recording. Once I had my pot turned to 150K, I added my record label so I would know where the "normal" speed was at. I just printed a Run DMC sticker on some label paper and added a little extra glue.

To record, place the onboard mic up to your speakers and hold the REC button when your sample comes on. The module will record as long as you hold down the REC button. It stops recording once your time is up but it doesn't look like the LED goes off. You get what you get.

The quality of the playback is not bad. I was thinking of desoldering the mic and adding an audio jack there so I can plug a cable right into my Walkman headphone jack. I think the quality might be a little better that way, but it seemed like too much effort.

You should be all set to rock the party.