Exhale

This video got me thinking about breath controllers. The idea is to use a pressure sensor, such as the NXP MPVZ4006GW7U, to generate MIDI data… or you could generate a control voltage.

It seems to be common to use a melodica mouthpiece and tube for these projects. Apparently they fit nicely on the sensor.

Fortunately, you can get those without having to buy a whole melodica. I have one of each of the above on order.

I’ve done some thinking in the past about a DIY wind controller but that’s rather more ambitious than I’m ready for. But just a breath controller (CV, rather than MIDI) should be pretty easy. In fact the MPVZ4006GW7U is practically a CV breath controller by itself. I mean, you have to feed it 5 V, and you need to attach the tube, but then the output pin can go right to the synth, I think.

Though there’s an offset. It puts out about 0.3 V when there’s no pressure, which is probably okay for controlling a filter cutoff or pulse width or something, but what about a VCA? I’m not particularly skilled at electronics design (to understate it) but I was working on drawing up a circuit to cut off the sensor output voltage when it’s below a threshold, using diodes, followed by an amplifier to get the 0 to 5 V range back. Then I found I might not need it, at least for the Mother-32 VCA. I tried plugging the VC mix out into the VCA CV with no inputs to the VC mixer, so it acts as a voltage source you can vary with the knob from 0 to 5 V, and at 0.3 V I can’t hear anything. Seems there’s a threshold before the VCA turns on. That’s good, at least for this project.

However, experimentation may perhaps convince me the sensor output could use some other sort of processing. Maybe a nonlinear response is desirable, or a gate output would be useful. Both seem unlikely but who knows? If so, doing it like the ribbon controller with an Arduino and a DAC would probably be the way I’d go.

More fairly cheap thrills. The sensor goes for about $13. I got the mouthpiece and tube on eBay for $6 and change (from a US seller; I think there are even cheaper ones shipped from China.) Pretty sure there’s a 5V Arduino Pro Mini sitting around unused in my stash if I need it. I didn’t have another DAC chip but I’ve ordered one. If I don’t use it for this maybe I’ll find another use for it. And if I decide I need that analog circuit after all I think I have all the parts for that. Eventually there’ll be perfboards and project boxes and Eurorack panels to think about, but those come later.

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