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Diy optical pickup for guitar -- is it possible?
sorveltaja:
This time, the audio recording of the 6-to-1 mixed schmitt triggers was done straight to the laptops mic input. So no echo, equalisation or any other effects were used. Plain 'dry' output:
(zipped mp3 attached)
The schmitt triggers' output was bit too hot for the laptops mic input, so I did simply put a potentiometer between them, to the breadboard to turn down the excess distortion. That breadboard was on my lap, while plucking the strings, and kept on falling all the time..
But after all, I was just too impatient to test the audio output, to solder some wires for more usable/permanent level adjusting unit.
When doing the previous, failed recording, when there was that weirdo cancelling effect, I used Zoom G3(guitar effects device) between the schmitt triggers and laptop.
I'll have to admit, that for a long time, I have been interested in exploring odd and strange audio effects. But that one, I can't even imagine, how to track it, or make sense, what it actually is.
Besides all that, came another idea of using individual covers for each string/pickup, like this:
]
I haven't tested that yet, but if it works, the parts could be printed, while being a lot more 'stealth', than single, bulky cover.
sorveltaja:
At this point, it's (finally) time to move on to making the electronic circuitry(amp, schmitt trigger, and ir-led adjustment -boards ) in more easily form to operate. That means basically removing them from the guitar body.
As the guitar is to be used only at the living room, for starters, one meter long cables should do. The plan is to use 7 for the ir-leds(could possibly be made out of an ethernet cable), and 6 for the senders/receivers(using shielded microphone cable).
I already tested a single pickup with a single, one meter mic cable, and so far, it seems to work. The end result, with all the cables/pickups connected, could be lacking, what comes to noise levels.
But as always, there is only one way to find it out.
If (when)all goes well with the wiring, then comes time to test, of how the schmitt trigger outputs could be refined further, and to see, do they(running at 1,8V) need to be amplified/gated to feed external cmos-based devices.
PekkaNF:
--- Quote from: sorveltaja on February 08, 2020, 05:29:40 PM ---This time, the audio recording of the 6-to-1 mixed schmitt triggers was done straight to the laptops mic input. So no echo, equalisation or any other effects were used. Plain 'dry' output:
http://www.elisanet.fi/kz1706/optical_pup/testing_new_setup.mp3
......
--- End quote ---
Wow. I am surpriced that the output is that rich and even some warmth in it - like second harmonics or something "musical" distortion. Must be hard to find a sweet spot location for opto componenets.
sorveltaja:
--- Quote from: PekkaNF on February 10, 2020, 03:51:49 AM ---Wow. I am surpriced that the output is that rich and even some warmth in it - like second harmonics or something "musical" distortion. Must be hard to find a sweet spot location for opto componenets.
--- End quote ---
Pekka, yes, for some reason, that seems to be the nature of the true analog 'synth' -sound. Produced harmonics are certainly very complex, providing that 'something', which makes it sound the way it does.
So, that's how the analog hex fuzz sounds. There are some videos on Youtube about commercially available ones, but generally they have a lot more mellow outputs(probably to suit for larger user base), than mine has.
What comes to adjusting the height of the pickups for sweet spots, I'm not sure, but it could be done so-and-so just by listening the outputs, judging the result by how long the string rings, and therefore cause the schmitt trigger to 'squarify'.
To lessen the 'guesstimation' -factors, using a function generator and scope help a lot.
The process isn't that difficult, but can be tedious. Fortunately, it needs to be done only once(assuming the string heights remain the same).
sorveltaja:
After the wiring for the new enclosure is done, I'm going to test the idea of the previously mentioned individual pickup covers.
At first, for the enclosure, I thought about ordering a Hammond-like aluminum one right away, but decided to hack it together from pieces of wood I have lying around.
As the project is in testing phase, I didn't want to bother with possible need of the isolated/insulated connectors, that metal enclosure might well require.
Could take some time, as I'm not yet sure, what kind of connector to use for the enclosure outputs.
One likely candidate is a cd-rom ide-cable(which I already have at hand), that has more than enough pins(39) for possible 'extended' future options(like modulating each ir-leds individually, using external signals, if needed).
Also each schmitt trigger would have individual outputs for an external mixer, and/or other processing purposes(to convert square wave to a triangle/sine one, or to feed some envelope followers/filters/oscillators etc.).
Lots of babbling, but in short: the enclosure mentioned will include only the circuitry used so far. Rest is about making easily accessible connections for further testing, mainly for breadboard.
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