Working Microphone From Trash

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Introduction: Working Microphone From Trash

About: Father. Husband. Artist. Musician. Teacher.

This isn’t another misleading clickbait tutorial, this is a genuine step by step guide to make a humble, yet great sounding microphone that can be used in a variety of applications. Don’t be disillusioned, this microphone will not replace professional studio microphones, but they are robust, reliable, and recyclable. The price tag associated with the construction of this microphone is also not clickbait, ALL the materials needed to construct this microphone can be found for FREE.

(The tools used throughout, however, do have an associated cost. Don’t be discouraged by this, simply find alternative methods to achieve the same results. Get creative! )

Supplies

What you’ll need to recreate this project:

A piece of PETE 1 or PET 1 plastic (thoroughly washed )

A tin can with a ROLLED lip on both ends (also thoroughly washed )

An audio jack of some sort (1/4’’, 1/8’’, RCA, XLR )

A switch of some sort (optional )

A length of wire (preferably two different colours )

Step 1: Sourcing the Right Recyclables

  • The tin can and PETE 1 plastic can be found in your recyclables (technically not entirely free so my suggestion is to source them instead from your neighbours…).
  • When sourcing the tin can, look for one that has a ROLLED or FOLDED rim (first image ) on both ends rather than a seamless bottom (second image )

Step 2: Sourcing the Electronics

  • Your best bet for the audio jack, switch and lengths of wire would be to salvage them from an old radio or tape recorder. Basically, any sound or music related device is a good place to search for these parts.
  • The piezoelectric element can be a bit trickier to source, but they are still prevalent in consumer products that *beep* such as microwaves, alarms, buzzers, children’s toys, etc.

*Be sure to read and heed all warnings before dissembling anything you are unfamiliar with !

Step 3: An Explanation

So, Mr. Ham, how are we turning a pile of recyclables and some salvaged electronic bits into a functioning microphone? PLASTIC! Let me explain. Membranophones, a family of instruments with membranes such as drums, produce sound via a vibrating membrane that pushes air in waves which crash onto the beaches of our ears.

Our microphone will work identically, but in a completely opposite way. Let me explain further. When a person or instrument produces sound, air is displaced in audible waves stemming from vibrating vocal folds, strings, membranes, reeds, lips, etc. Those sound waves of air will crash onto a thin plastic membrane stretched over one of the ends of the tin can and cause it to vibrate.

We will capture those vibrations and transform them into an electrical signal that can be amplified by attaching the salvaged piezoelectric element to the membrane. Piezo elements (or transducers ) translate minute movements into minuscule electrical pulses which can be amplified into usable audio signals and can then be projected through loud speakers.

How will we be making this thin plastic membrane to catch the vibrations of everything that we want to record? I’m glad you asked. Onto the next step!

Step 4: Polyethylene Terephthalate?

To produce our membrane, we are on the hunt for the extremely versatile thermoplastic –Polyethylene terephthalate. This plastic sounds exotic but makes up roughly 60% or more of consumer plastics, so there’s a good chance that you’ll find something made from it in your (or your neighbour’s) recycling bin!

It’s the type of plastic used for beverage bottles, polyester, carpets, mylar, as well as countless other food storage applications, and can be easily identified by it’s recycling symbol: PETE 1 or PET 1. I’ll be using an empty juice container for my microphone. I implore you to recycle the offcuts as it’s virtually the most recyclable plastic that is produced.

Step 5: Magical Membranes

In this step, we’ll be exploiting the thermodynamic properties of that not so exotic plastic to produce a durable yet sensitive plastic membrane.

*Peppered throughout this Instructable are tips and tricks to help you make the process efficacious and safer, based on my personal experience. If you’ve found a better way to anything mentioned, please don’t hesitate to share it so we can all learn!

Tip for cutting up PETE 1 plastic bottles:

Clamp a razor blade in a vise at a 45° angle so that only a ¼ of an inch sticks out proud of the jaws of the vise. Then, by holding the bottle by both ends horizontally, pierce the flat center section of the bottle by applying firm pressure against the blade. ½” Once the bottle has been pierced, spin it to cut the length of its circumference. After you succeed at cutting the bottle into two pieces, use scissors to cut perpendicularly to your initial cut and proceed to cut the middle section of the bottle into a useable sheet of plastic.

After cutting out a useable sheet from the PETE 1 plastic container that you are using, draw or trace a circle that is a 1/4 inch in diameter larger than the tin can that you are using. This can be a rough eyeballed estimate.

*Refrain from using a compass directly on the plastic sheet as you want to avoid piercing the plastic if possible. Instead, use the compass to draw an appropriately sized circle onto a piece of thick cardstock or corrugated cardboard, cut the cardstock/cardboard circle out and use it to trace a circle onto the plastic sheet. Another alternative is to find a round object that is relatively close in diameter to your desired size and use it to trace a circle onto the plastic sheet.

Now for the magic bit.

Step 6: Preparing the Tin Can

After thoroughly washing out the tin can, remove the unopened end of the tin can with a can opener. Then drill two holes into the side of the can at 90 degrees from one another about mid-way up the can. I used a stepped bit to do this and clamped my can in a vise to secure it in place while I drilled the holes. One of the hole's diameter must be large enough to accommodate the jack you are using and the other hole large enough for the switch you are using.

Step 7: The Somewhat Productive Susan JIG

The next step is the trickiest bit of this build, but this simple ''jig'' should make things a bit easier. Cut a scrap bit of thin, heat resistant-ish material to roughly 12'' x 12''. Next, place your PETE 1 plastic disc (as close to centered as possible ), followed by your tin can, followed by another scrap piece of anything large enough to span the diameter of the tin can, and finally a weight of some kind (I’ll be using a Ham-mer ). This setup should allow you to spin the tin can and PETE 1 plastic disc with little resistance, you'll see why this will come in handy during the next step!

Step 8: Stretching and Affixing the Membrane by Using Heat

Now for the tricky bit. Move your setup to a well-ventilated area, outside is always best and start by holding one of the corners of your Somewhat Productive Susan Base so that it faces you.

With a heat gun (or blowtorch), apply steady heat just above the rim of the tin can, kissing also the surplus plastic until it curls and starts to wrap around the rim. Once the plastic starts to curl around the rim, spin the base of your setup so that the plastic curls up around the entire circumference of the rim of the tin can. Avoid staying in a single area with the heat gun for too long.

*But how long is too long? If the plastic starts to discolour by turning an opaque brown or yellowish colour or small bubbles appear in the plastic, then the area was heated for too long.

Continue heating and spinning until the plastic hugs the rim of the tin can tightly and the excess above the rim is undulated evenly. Let everything cool for at least 5-10 minutes then remove the tin can from the jig. Flip over the tin can so that the plastic membrane is facing up. Upon flipping over the can, you might notice that the surface of the membrane is a bit wrinkly. To tighten it up, apply a gentle even heat with the heat gun over the surface of the membrane, moving the heat gun side to side constantly until the wrinkles disappear. After allowing the plastic membrane to cool for a few more minutes, check that it is tight by rapping it with the eraser end of a pencil, it should sound like a tuned drum.

Step 9: Installing the Electronics

The 0$ microphone relies on simple electronics to function. To make the process painless, I’ve provided a visual wiring diagram.

I’ll be using thin gauge solid core wire for the wiring in this project. I’ve had better luck over the years with solid core wire when soldering to piezo elements as the soldering iron’s contact with the piezo element is kept brief. Using an old microphone cable for this project wouldn’t be a bad idea either as its shielded!

When soldering to a piezo element I always suggest using a heatsink to avoid damaging the fragile element, especially if it's your first time. If you do not have a heat sink, any thick piece of metal in conjunction with solid core wire and brief contact with the soldering iron should provide the piezo element with enough protection against overheating. I’ve also soldered to them without any heatsink of any kind successfully, so don’t fret.

Another thing you can do to make the piezo element more robust is to add some hot glue to the connection points.

After everything is wired up, TEST YOUR CIRCUIT. Do this before installing everything. After testing that your circuit works as it should, simply glue the piezo element to the inside of the membrane using a dab of hot glue or 5-minute epoxy. Then install the audio jack and switch into the holes we pre-drilled earlier.

Step 10: Can You Hear Me Now?

Your $0 microphone is now ready for your next gig or recording session! Simply plug it into an amp or P.A. and turn it on! You will be impressed by the sound and will find plenty of uses for it either in the studio or live. One cool trick is to hold it by the cable and swing it in front of the speaker of an amplifier to get cool feedback effects!

Also, the condensation that builds up on the inside of the membrane doesn't seem to have any advert effect on the sound of the microphone. This is also a great kick drum microphone and in fact you can even use it as a percussion instrument!

But Mr. Ham is it robust enough to gig with? ABSOLUTELY! I've had the one illustrated (green membrane) for close to 10 years and it has always worked perfectly.

Want to hear it in action? Check out this improvised vocal riff I've entitled ''Quarantine'', enjoy!

Rock on!

Mr. Ham

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    18 Comments

    0
    coyotefingers
    coyotefingers

    24 days ago

    THANK YOU for posting a real tutorial instead of the same goddamn "new and improved here buy this" link jfc bless you man

    0
    ChristinaA21
    ChristinaA21

    3 months ago

    Neatly done! This might also be an amazing base for an easy flat coil plus magnet speaker - I am thinking of physics classes...

    0
    PaulG429
    PaulG429

    1 year ago

    Using a 'transducer' element is cheating IMHO ...and where would I find one easily ? I would prefer to see something with a magnet and voice coil attached to the membrane (especially from a HAM)...it would need to be amplified tho due to the lower output just like a dynamic vs condenser mic... 73 de K9PLG

    0
    Ham-made
    Ham-made

    Reply 1 year ago

    Hey PaulG429!
    If you want to be an electromagnetic purist, you can use the winding of a small battery powered motor. I've used small motors plenty of times to make electromagnetic pickups for homemade string instruments. Honestly, the piezoelectric condensers are easier to find than you might think, the best place to score them is in kids drum machine toys. The pads that you strike to activate the different sounds use piezoelectric discs to achieve the effect. Or you can salvage them from the fire alarms in your home the next time that you replace them.
    Cheers!
    Mr. Ham

    0
    pcorbett
    pcorbett

    Reply 7 months ago

    Piezoelectric discs are clever low tech gizmos that are everywhere and are super cheap if you choose to buy them from cigar box guitar parts vender. They also can be cut in half or you can trim them and with a small collection you can experiment freely and cheaply. To repeat the list : anything used as an alarm such as clocks, fire alarms, and timers (microwave oven) it's also used as a sensors to stop vacuum cleaner heads from overloading with sometimes two large ones . I found good ones in the rain sensors of a (Velux ) skylight used as a rain sensor but rare to retrieve due to the skylights are not old enough yet for replacement. In a nut shell its speakers, microphones, and vibration detectors. I have wired and hot glued one to a clothespin to clamp onto canjos and such. Nice work Ham...

    0
    NathanL50
    NathanL50

    Reply 1 year ago

    Definitely. It's like saying you're building a car from scratch when all you're doing is building a frame around a motorised go-cart. Piezoelectric microphones are very common eg as found on acoustic guitar pickups.

    0
    schaapkameel
    schaapkameel

    Reply 1 year ago

    Nathan, I must disagree. Piezoelectric mics are known for their fantastic high output-thinny-sound when surface mounted. However, they are hardly affected by soundwaves through the air. This instructable fixes that with quite an ingeneous membrane.

    0
    DavidH291
    DavidH291

    Reply 1 year ago

    Any easy place to find a piezo buzzer is in a musical greeting card.

    0
    onetruegod
    onetruegod

    Reply 1 year ago

    I agree, this does make the title clickbait both in account of using the piezo and the "Free" claim.

    0
    jackreno11
    jackreno11

    1 year ago

    A very impressive project indeed! I'll surely have to give this a try someday. Perhaps with my kids when they're old enough.

    While reading through, I saw the ham-mer and immediately thought "no way! that guy?" and sure enough! It's so cool that a whole year later another one of your Instructables has caught my eye. Well done mate!

    0
    KetkA
    KetkA

    1 year ago

    Hola. Muy interesante micrófono. Por su sencillez, me ha recordado al de Graham Bell en la maceta de arcilla y la membrana de piel de conejo. Y me ha gustado mucho la simplicidad de los materiales empleados. También me ha llamado la atención la pasión con la que has cantado. Además tiene un ligero efecto de sonido. Muchas gracias por haber compratido en vídeo un montaje tan interesante. Un cordial saludo.

    graham.jpg
    0
    Ham-made
    Ham-made

    Reply 1 year ago

    Hey KetkA!
    My Spanish is a bit rusty, but from what I can deduce, I love your comparison to Bell's first experiments with membrane based microphones! In fact, as a side note, the town that he's from is about 30 minutes from where I live now! Thank you so much for the kind words, I'm glad that you got something out of the performance. I was just improvising as I went along! Part of why I love these microphones so much is their simplicity. In fact, the same electronics can be applied to a variety of different materials, experiment and have fun!
    Cheers!
    Mr. Ham

    ¡Hola, KetkA!
    Mi español está un poco oxidado, pero por lo que puedo deducir, ¡me encanta tu comparación con los primeros experimentos de Bell con micrófonos basados en membrana! De hecho, como nota al margen, ¡la ciudad de la que proviene está a unos 30 minutos de donde vivo ahora! Muchas gracias por las amables palabras, me alegro de que hayas sacado algo de la actuación. ¡Estaba improvisando a medida que avanzaba! Parte de por qué amo tanto estos micrófonos es su simplicidad. De hecho, la misma electrónica se puede aplicar a una variedad de materiales diferentes, experimentar y divertirse.
    Saludos!
    Señor jamón
    0
    CraigH6
    CraigH6

    1 year ago

    Ham-made, excellent project, so simple, unique sound, quite haunting. In the video, were you using the amp's reverb? Just curious. BTW, the YT video description doesn't include a link to this instructable. I'm definitely going to make one of these and try it out. Thanks.

    0
    Ham-made
    Ham-made

    Reply 1 year ago

    Hey CraigH6! In the video I did use the amp's reverb, as the sound was a bit dry without it. Thanks for the YouTube description comment I will fix that immediately, good catch!
    Cheers!
    Mr. Ham

    0
    StevenB236
    StevenB236

    1 year ago

    Will this work as a pc input?

    0
    Ham-made
    Ham-made

    Reply 1 year ago

    Hey StevenB236, absolutely! Only I would suggest using an 1/8" audio jack instead of a 1/4" audio jack like I used just to make it easier to connect it to your PC.
    Cheers!
    Mr. Ham

    0
    M3G
    M3G

    1 year ago

    Wow, that sounds great! I'm impressed. Love the song too, haha.

    0
    Ham-made
    Ham-made

    Reply 1 year ago

    Thanks M3G! It's the best sound you can get for free!

    Cheers!
    Mr. Ham