[Project] Mikrophonie Peizo Contact Mic Module

Tombola · Post by **Tombola** » Thu Jun 05, 2014 3:43 am

UPDATE:

The design files are now up: Mikrophonie Contact Mic Documentation.

You'll find:
Documentation
Schematic
BOM
and full PCB design files.

This is a very simple circuit; apart from the 3.5mm jacks (which are Erthenvar / Thonk) pretty much everything should be available from your parts drawer or from Radio Shack / Maplin / Bitsbox. The PTC fuses may be hard to find, but any PTC fuse with a trip current above 100ma and 5mm lead spacing will work.

None of the component values are super critical, but changes will obviously effect gain levels. A pot below 50k will reduce the gain range, a larger pot will increase it.

The two PCBs (circuit and panel) are optimised for Seeed Studio Fusion PCB - you can buy 5 sets for about $65.

As usual, this is Creative Commons licensed: CC BY SA

Alternatively, WAITING LIST FOR THONK ORDERS IS HERE

British-made contact microphones with 3.5mm jacks are available from Jez Riley French.

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My next design is currently being beta tested. If all goes well, I'll release the design files for this in the next few weeks.

Mikrophonie is a very simple contact mic module. There is a small piezo disk mounted behind the 4hp panel, or you can plug in an external mic (they're very easy to make).

The panel is PCB with no soldermask. The raw PCB fibreglass has quite a nice rough texture - rubbing it with a finger or a plectrum creates quite a wide range of sounds. The back of the panel is plated and grounded for shielding.

The mic will also pick up all the physical sounds in your modular - patching, cables rustling, switches, fingers on knobs - without picking up airborne sounds i.e. the sound your modular is making. At very high sound levels will pick up vibrations from the speaker output and start to feedback.

Here are a couple of great demo videos from Leafcutter John and Robin Rimbaud:

[video][/video]
[video][/video]

And here's a sound clip of the module picking up patching noises, feeding back through an Echophon

Here's a much cleaner demo of the built in microphone, just picking up the sound of the switches and knobs:
[video][/video]

Synesthesia · Post by **Synesthesia** » Thu Jun 05, 2014 3:55 am

Brilliant!!! can't wait to try that

vurma · Post by **vurma** » Thu Jun 05, 2014 4:42 am

Will combine well with theremin modules and the Teleplexer.

oootini · Post by **oootini** » Thu Jun 05, 2014 4:55 am

awesome.

horstronic · Post by **horstronic** » Thu Jun 05, 2014 5:14 am

That's awesome!
I was acutally thinking about building something like that. Now I don't have to design it by myself

Post by **Rigo** » Thu Jun 05, 2014 5:35 am

Will there be Thonk kits ? I should really start ordering components for all the things I have to make, so it's not a problem if there weren't any kits (except going through all those boms and counting components, that is).

okelk · Post by **okelk** » Thu Jun 05, 2014 5:37 am

Nice! I imagine scratching my fingernails on that surface must be really fun!
Does the Mikrophonie has special circuitry for piezo pickups or is it just a regular preamp?

julien · Post by **julien** » Thu Jun 05, 2014 8:34 am

I will keep my fingers crossed for a Thonk kit

The panel looks great but it could be awesome with black finish 8_)

grilojoe · Post by **grilojoe** » Thu Jun 05, 2014 8:39 am

I do love contact mics. This looks like loads of fun.

Tombola · Post by **Tombola** » Thu Jun 05, 2014 8:46 am

okelk wrote:Nice! I imagine scratching my fingernails on that surface must be really fun!
Does the Mikrophonie has special circuitry for piezo pickups or is it just a regular preamp?

It's optimised a bit - very high impedance, pretty large gain range, and diodes to protect the op amp from the very high voltages the piezo can produce.

If you had a dynamic mic on a 3.5mm jack, that would probably also work, and you can certainly use it as a super high gain fuzz/boost for modular level signals...

Tombola · Post by **Tombola** » Thu Jun 05, 2014 8:50 am

julien wrote:I will keep my fingers crossed for a Thonk kit

The panel looks great but it could be awesome with black finish 8_)

That might be possible, but you'd lose the texture a bit. Brushed aluminium might work, but PCB has the texture, the shielding + you can just solder the mic straight onto the copper/gold back of the panel:

eole · Post by **eole** » Thu Jun 05, 2014 9:22 am

latigid on · Post by **latigid on** » Thu Jun 05, 2014 9:32 am

Awesome work, bravo!

Jarno · Post by **Jarno** » Thu Jun 05, 2014 10:25 am

Do they respond to bending (when you push on the panel) as well?

Tombola · Post by **Tombola** » Thu Jun 05, 2014 11:00 am

Jarno wrote:Do they respond to bending (when you push on the panel) as well?

It does, but the voltage is generated in proportion to the change in the flex, not to the flex itself

i.e. while you push, you get voltage, but if you hold the panel in, the voltage drops off. Then while you release the panel, the voltage goes up.

That's the principle - in fact, if you're holding your finger on the panel, you'll get massive crazy voltage fluctuations - as if you were pushing the diaphragm of a microphone.

So it doesn't really work very well as a pressure sensor - it isn't a Force Sensitive Resistor

But it does work well as a trigger - connect it to a LPG and you can ping by tapping the panel - good for bongos

Jarno · Post by **Jarno** » Thu Jun 05, 2014 11:35 am

Sounds interesting, a bongo module. Might make sense to place the soldering joints top and bottom only.
Thanks for this!

BugBrand · Post by **BugBrand** » Thu Jun 05, 2014 4:29 pm

Hey Tom, a couple of thoughts::

- that piezo you've got is one that I seem to remember is described as being 'with feedback' - but looks like you're connecting to the larger area piezo bit anyways? I seem to remember testing those f-back ones years ago and not finding them so great - but think that was connecting to the small area.
(used to get raw 27mm ones from JPR Electronics - http://www.jprelec.co.uk/store.asp/c=93 ... c-Elements)

- for the panel it shouldn't be too complicated to still provide a soldering point for the piezo on the back while also covering the rest (front&back) with soldermask if required. (you can make something with soldermask stop area fairly easily in Eagle)

- initial thought was that that nice design on the front could provide extra surface tactility, especially if you chose to use 4oz copper (not always very much more expensive) - you really then notice the thickness and you could perhaps play more with the patterns.. (could again perhaps have some areas without soldermask / bare PCB material.. dunno)

I can't count, can I?!

Tombola · Post by **Tombola** » Thu Jun 05, 2014 4:56 pm

BugBrand wrote:Hey Tom, a couple of thoughts::

- that piezo you've got is one that I seem to remember is described as being 'with feedback' - but looks like you're connecting to the larger area piezo bit anyways? I seem to remember testing those f-back ones years ago and not finding them so great - but think that was connecting to the small area.
(used to get raw 27mm ones from JPR Electronics - http://www.jprelec.co.uk/store.asp/c=93 ... c-Elements)

Yes, these seem to work fine - I'm just ignoring the little 'feedback' area.

But those JPR look really good, 20mm diameter for 20p (with wires) vs 91p for the mouser ones I used for the proto.

BugBrand wrote: - for the panel it shouldn't be too complicated to still provide a soldering point for the piezo on the back while also covering the rest (front&back) with soldermask if required. (you can make something with soldermask stop area fairly easily in Eagle)

Yes, that would work - although on all my earlier protos, I just epoxied the piezo. I only soldered it here because it seemed like an easy way to attach it. The electrical connection is made by the black lead anyway (though that's not necessary if soldered)
It's possible that the firmer (ie across a wider surface area) connection from epoxy would work better acoustically.

BugBrand wrote: - initial thought was that that nice design on the front could provide extra surface tactility, especially if you chose to use 4oz copper (not always very much more expensive) - you really then notice the thickness and you could perhaps play more with the patterns.. (could again perhaps have some areas without soldermask / bare PCB material.. dunno)

Yes, that was exactly the intention - the 4oz copper is a really good idea. In the Leafcutter video you can see him strumming the copper with a plectrum!

mckenic · Post by **mckenic** » Thu Jun 05, 2014 5:00 pm

Brilliant - just so cool!!!

Man I hope you keep coming out with these crazy things!

Thonk Support · Post by **Thonk Support** » Thu Jun 05, 2014 5:08 pm

Thonk kits of course

http://www.thonk.co.uk/shop/mikrophonie/

mapmap · Post by **mapmap** » Thu Jun 05, 2014 6:31 pm

Very cool!

Thonk Support · Post by **Thonk Support** » Fri Jun 06, 2014 3:44 am

If you chose to solder a contact mic to the rear of the Mikrophonie faceplate, then when the external mic is not connected.. and if you choose to patch it in, every physical interaction with your modular can produce sound. One for the zen masters.

[video][/video]

KNYST · Post by **KNYST** » Fri Jun 06, 2014 5:33 am

thank you Tom(bola)

I've been thinking about making something very similar to this. Definitely in for a kit or two

Tombola · Post by **Tombola** » Fri Jun 06, 2014 2:35 pm

Another shot of the panel:

scorbie · Post by **scorbie** » Tue Jun 17, 2014 8:32 am

I'm having this.
Is there an ETA?
Looks like a lot of fun!

MOD WIGGLER

MOD WIGGLER

[Project] Mikrophonie Peizo Contact Mic Module

[Project] Mikrophonie Peizo Contact Mic Module