 Hello, and welcome to the show. It's me, John Park. It's time for John Park's workshop. And I'm just having a good laugh because I posted over in our Discord chat, which is right here at adafru.it slash discord in live broadcast chat channel. I had posted a little icon of coffee, and it's a terrible icon. Look at this thing. It looks like, as I say, a couple of worms that are gloating over the fact that they've ruined your coffee. Except our friend Steve, okay, you're unpointed out that on your phone, it looks great. The Discord client on the phone has a beautiful coffee cup. I didn't really think about the fact that iOS versus a browser-based solution for Discord has totally different emojis. What the heck? But Steve, I don't know. He made me happy with that boba tea, so that's something right there. Also hello to the good people over in our YouTube chat. If you're wondering where all these chats are happening and you're somewhere like Twitch or Facebook, I can't watch all the chats, so mostly I'm here on our Discord right there and checking out our YouTube chat. So thanks everyone for stopping by in those places. Let's see, what else is up? Hello to my friend Kurt if you're watching. My friend Kurt may be watching, and I don't know if he normally watches, but Kurt, hey, hope you're watching. Let's see, what else is going on? I got back from a vacation. We went to London, and among the other cool things that happened there was my wife spotted this t-shirt at a little shop we were at in, where was it? In where all the vintage clothing is. What's that neighborhood there? I forget now. Anyway, she found me this shirt that's got all of the London Underground as a cassette tape and a bunch of music styles, which I dig. Short itch, it wasn't short itch, but near short itch. I can't remember. Hey, Mark DeVink. Mark DeVink is over in our YouTube as well. Nice to see you, Mark. Does everyone appreciate the fact that Mark has been making these amazing LEDs that we're selling now over in the store? Check these out. Deluxe Delight. This is a cat, and it's an LED. Look at that. He's got a whole bunch of them. Do we have a link that's all of them? Let me see. There's gotta be. Surely there is. How about D Luxe in our search? Look at these. Cats, a couple colors of cats, three colors of cats. A little aloe vera, it's a little succulent kind of guy there, some skulls, crystal, cone, sphere. Awesome stuff. So way to go, Mark. Thanks for sharing those with the world, and go buy some. If you're looking for something fun to throw in your cart, you can get a little three pack for $9. $9, $10 depends. How are you making those, by the way? Is this 3D printed resin? Is that what you're doing? Did you make a mold? I don't actually know how you're making these, so please let us know. We wanna know. All right, what else? Let's see. We have a job board if you're looking for work, or if you are looking to hire someone, head on over to jobs.adafruit.com, and there you can join in on the fun. Let me go there right now in my browser and share that with you. Here's jobs.adafruit.com. It looks like that. You can search through here if you're looking for a particular job, or if you're looking to hire someone with a particular skill set. Head on over here, it's free to use. All you need is to sign up with an email address. We promise not to spam you. And all of these are vetted with the utmost of care by Lamor and PT, so presumably all legit. I don't know what guarantee we have on that, but that's a presumption, right? Jobs.adafruit.com, go check it out. Also, let's see, I'm keeping an eye on the chat because maybe Mark will let us know how he's building those LEDs. How are you making them? They're great. So, Bornox, it's Spatial Fields Market? No, what the heck was that? There was a, you know, the bee? This was just days ago, and I've already forgotten. Pardon me. All right, I'm sure it'll come to me, or someone who knows London will. So, what else? I've got a show on Tuesdays that some of you may have caught. It is called JP's Product Pick of the Week. That's the little logo right there. And on the show each week, I like to show off a cool project, a rather product. This week it was this Neopixel 332 per meter strip. It's a half meter, so about 166. And I'll do a little bit of a demo. We got a half price on this during the show. No coupon code needed, you just buy it and it's cheap. And I will show you a little recap of it. The Neopixel 332 silicone bead LED strip. It is a half meter, so there's 166, I believe, LEDs in there, and it is gorgeous. So this is individually addressable Neopixel LEDs. I've plugged it into a QT Pi RP2040 with a little battery BFF and a little lipo battery. And as you can see here, you get a really nice, nearly solid display. You can see as they dim there, they will start to reveal the trick. But at more moderate brightness levels, and this is only at, I think, 0.35 on brightness, it almost looks like a continuous neon strip, except it's got this individually addressable RGB effect to it, which is really cool. That is my product pick of the week. It is the Neopixel 332 silicone bead half meter LED strip. All right, I remembered it was Burrow Market. That's where we were. This was really important to remember this. Burrow, Burrow Market. Got some good cheese there from a cheese monger, too. That was the question, Mr. Certainly, if you were wondering still. All right, let's see, what else is going on? Hey, this is a great time to do a little circuit Python parsec, where I'll give you a little tidbit of how to do a certain thing in circuit Python. So check it out. Let's do it. All right, let's do it. Let me just find my coding window there. OK, for the circuit Python parsec today, I wanted to show how you can use the pixel map inside of the LED animation library to separate a Neopixel strip into different logical groupings. So one physical strip, multiple logical groupings, it allows you to do some really neat stuff, and essentially in code, treat this like it's two strips. But you can see here, I've got one ring here. It's a ring of 24 Neopixels. I have a little diffuser on there to make it a little easier to look at under the camera. And I'm using two separate Comet animations, running at different speeds with different colors, treating it like two strips, not four, but two. Here's how we do it. In code, I am importing the board library to get pin definitions and the Neopixel library. Then I'm bringing in three sections of the Adafruit LED animation library. I've got Comet, which is the animation effect that I'm using here, a couple of color definitions, purple and green, and then this pixel map business. So I set up the strip. And you can see, this is the normal Neopixel definition. So I'm just saying it's a 24 pixel strip on pin A1, and I'm setting the brightness pretty low, 0.05. Then I set up these two logical pixel map groupings, leds range A and leds range B. You can name those whatever you want. And then there I use the command pixel map, leds, which is the Neopixel strip. The range that I'm using, the first one goes from 0 to 11, and then the second one goes from 12 to 23. Just tell it the outer bound number there. And then I'm setting up a couple of these different animation objects for Comet. Then I fill the whole thing with black, so it turns them all off. And then the main loop of the animation just simply says, run those two animations. So any changes you want to make to one of these, you can do it, and it doesn't affect the other one. And so that is how you can use pixel map in the LED animation library to set up multiple logical groupings of Neopixels on a single physical strip. And that is your Circuit Python Parsec. All right, and thanks again to the creators, Rose and Catney in particular, but also others on the Circuit Python team for making that LED animation library. If you haven't used it, check it out. There's so much you can do with it. I'll do a few other tips with it. I've done some, I think in the past. I've also done some projects like the revised version of the Lucio Blaster. It's over there, but I'm not going to get it right that uses the LED animation library to make life really easy to set up some really cool effects. All right, let's see what else is going on. Hey, there's a cool, what's this cool animation all about? Yanisku, a little gif there. By the way, a Discord tip, there's a setting where you can tell it not to autoplay animation so it doesn't distract you until you mouse over. I use that, but you can tell it says gif in the corner, I think. Let's see, what else? Oh, thank you, yeah. DJ Devon 3 said a nice demo of the composite video nubshank in the monitor in the background. That's that dolly clock with the vapor wave action going on there. And I think it's still in pretty good time. I'm not grabbing it off the network regularly. I just set it up once, but the thing actually keeps a good time with its own timer in the microcontroller. Let's see, Rich Sad says, I have a number of questions about advanced use cases that I don't see how to support. Yeah, if you're talking about LED animation library, that's the thing. It's got a bunch of preconfigured things with some settings you can tweak on them, but some stuff you just can't do unless you get that feature added to the library. So it's not Neopixel itself, and then coding things, maybe even using async.io. That's the way to get really exact stuff, but you can get a lot of really cool effects based on those pre-canned effects and a few knobs that you can twiddle on them. For example, one I've seen with Comet and maybe someone else knows how to do that, but if you look at my down shooter here for a second, you can see I've got this purple Comet there, and I've set the tail length and the speed and the direction. I'm not having it bounce. But I don't really know in LED animation library how I could have multiples of them coming one after another. Maybe it's possible, but it's sort of, by definition, trails everything all the way off before it starts the next one. And I think that's just the nature of it. It's a convenience library, but it's not going to make every possible thing you can imagine possible. Let's see. What else? I think that is it for stuff going on over in the chat. So what I wanted to do next is this would be a cool time to do a bit of a gear report, and then we'll get into the main project. So let me go grab something off the workbench. I'm going to do it right here just because I'm out of space on the workbench. This is another London-related thing actually. Let me grab. So I'm grabbing my iPad here and dropping things. Let me see. That, let me put that on a little stand so it's at an angle. Hold on one second. Oh, that's terrible. OK, well, it's going to be smudgy and reflective. But hey, let me pause that. So this is what I wanted to show off. I was able to meet up with Tom Whitwell when I was over in London. Tom, as some of you who are into synthesizer-y things or music things, might know Tom and his company Music Thing Modular. And this is a really cool little riff on the 16n fader bank that he calls the 8MU. And it is, as you can see, eight little faders. It has an at-sam-d21 in there. And it is running some Arduino code. I think at first he was doing some stuff in circuit Python with it. You could probably get circuit Python back on it. But for the responsiveness he was looking for, he went with Arduino on this. And it has an IMU in there. So it can do some tilt control things. And it can use these faders, as well as some really neat little sort of side-mounted buttons. USB-C connector there. It's designed to send MIDI messages, MIDI CC messages, or MIDI notes out. It's configurable, both with some presets on here, as well as in code, if you want to flash it with new firmware. And I just wanted to do a little demo of it, because I found this is really cool for iOS music stuff. So if we jump over to the down camera here. And you can see here I have a version of a fork of VCV rack called MIRAC, or MIRAC. And these are little virtual synthesizer modules. What I'm going to do is connect up one of these little Apple on-the-go camera adapter thingies. And then over USB-C, I'm going to plug in. Let's see if I can put it in that way. Plug in the little fader bank, and 8MU. And actually, let me plug. I think the order you plug it matters for iOS to recognize this. OK, let me try. The other way. Uh-oh, bad demo. It's not responding. Oh, I'm not playing. That's why. There we go. OK. I keep forgetting this. This is not something that VCV rack, which I use a lot more has, which is a, or at least it's not an obvious place like it is on the iPad here. This is a pause, but you can pause the entire synth. It's not just the audio, so it just stops visually responding. So the idea with this is that if I'm using this the traditional way, I'm going to go in there and nudge these little sliders around, which is kind of OK, but not great. But wouldn't you rather use physical sliders? So that's what the 8MU gives you. So I have four little oscillators with different clocks going in, and this is a little mixer. And so I can mix the audio levels of those as well as the harmonics. If you look at these little knobs on the top right of each of those four modules. Oh, and if this will work, I can also change the octave on a couple of them. Yeah, that just dropped. Just go to that one. And I click on that button. Anyway, it's really fun to see physical sliders move on screen when you move physical ones to see the virtual ones go. So that's something that makes me happy right there. So thanks, Tom, for that. And he's going to be selling these by a thunk, thunk.co.uk, which is the reseller for all music thing modular things, most of which in the past have been modules for your rack. This is one of the first ones that's a standalone physical gizmo. Great job with this. And thank you, Tom. Tom, by the way, did a lot of really neat stuff in this build. Let me unplug this and set this back over here. So if you look, first of all, very thin PCB material for the top and bottom here to keep the height of the thing low, this is a notched USB-C connector, so it doesn't stand up above it. It made it easier to fit it all in there. This is the side mount button here, so it can basically fit underneath this jack. This is a jack for classic serial UART style MIDI, which he said he's going to re-enable in some firmware that he'll send. And then more of these little buttons that are edge-mounted. Really cool. And then some instructions on the back on how to use it. And like I said, you can change the modes by using these side buttons, and that allows you to do things like enable or disable the accelerometer-based stuff. I think there's a tap detection as well as different arrangements of these banks. And I don't know if you can change MIDI CC numbers with those. I haven't messed with that yet, but really cool. So keep an eye out for that. That was a project I know has been a long time in the making, if you follow Tom, on social media, and exciting to see it very nearly out, very nearly completed. So all right, let's jump back into our main project then. Rich Sat asked, who made this? It was made by Music Thing Modular, aka Tom Whitwell. And if you have ever heard of a module called the Turing Machine, that's the one that people know Tom best for, one of the most popular modules, a random melody generator that's really cool. And I would say, of course, you can use this for music stuff, but I've shown before, these types of little MIDI faders are great for stuff like adjustments inside of Lightroom. If you're doing color correction in Lightroom, there's a great plugin that makes it possible to use MIDI faders to adjust things, and then you can permanently have an exposure value, a gamma correction, some different color, white balance stuff, all at your fingertips with sliders, which is really nice. The firmware will be open source. Yeah, everything Tom does is open source, so I assume this is no different. I don't think it's published yet, but it will be. And like I said, this is a riff on another project that's also open source called 16N. I don't know what the N stands for in that, but N is in Nevada. 16N is a larger fader bank that uses a teensie. But teensies are hard to find, and this one is based on a, well, also hard to find, SamD21, but maybe not as hard to find. Don't know if there'll be a kit version, or if anything, you'll just do the assembly of the PCB to sandwich the thing. Maybe solder on your sliders, I'm not sure. And I don't know if you could see it, but there are some surface mount LEDs under those that were glowing when it was on, which is cool. So thank you again, Tom, for that, and excited to have that in the arsenal. I was able to use that on the airplane, which is the perfect use. Oh yeah, so Steve says SamD21 also very hard to find as bare chips. So I'm guessing Tom secured the amount that he needed for his first run of those, hopefully, crossing fingers. The other thing, by the way, with stuff like that is you probably can, if you want to, you could probably code that to send out USB HID stuff, arrow keys, those sorts of things. So these types of devices are usually very configurable to do things other than just MIDI. All right, so now let's get to this project. So last week, I was away. The week before that, I did a bit of an introduction to the general tape looping, cassette tape stuff and multi-track stuff with a four track and so on. But what I wanted to do today is show you a specific use for this tape deck. What I'll do actually is I'll give you a little tour of some things here from my down shooter. So at the center bottom right-ish area, you can see there's a Walkman there that's partly opened up. And then I have some other gear there. There's a MIDI keyboard, so I can send MIDI commands out through this little USB MIDI hub called the RetroKits, RK006, and that allows the keyboard and a QtiePie to be hosted by a USB MIDI host, which means I can send MIDI commands from that keyboard to the little QtiePie that's at the center of the screen. QtiePie can turn those MIDI notes into voltage outputs for a deck. So there's a little stem of Qt cable there and there's that little quad deck. And then there's two mysterious cables running to the Walkman. So that is my speed controller. I'm essentially adjusting the speed of the motor in there with a range of, essentially, I've got about two octaves, I think, it's two volts and I'm treating it like two volts per octave. I need to do a little more testing to see how accurate that is. But it seems like I've got about 24 playable notes on there. So it feels like maybe that's two octaves. And then I'm running some effects just so it sounds cooler, so we can hear that. So what I've done is I have taped a continuous sine wave chord onto one side of a cassette. So it's just gonna play that, which is pretty boring, except once we can start changing the speed of the motor, we're essentially repitching this whole chord. And you could do that with anything. You could do that with a normal pre-recorded cassette. You could do that with just a single tone. You could do it with drums, but really this continuous tone is a great use for this type of a melaton, which is a tape playback with different pitches type of instrument. So it doesn't feel like it's speeding up and slowing down so much as it's changing pitches versus if you were to put a drum beat or a pre-recorded song in there, it sounds a little more like you're just messing around with the speed. So let me go over there and demo some stuff and show you how this all works and where we're going with it. So let me switch my camera over to there and head on over. And by the way, if you're over in the Discord chat, Steve just posted a link to an article about a melaton. So go check that out, they're really cool. I believe a melaton has a discrete tape loop per key. So there's a whole bunch of tape mechanisms in there. So it's a little more like multi-sampled rather than one sample that's being pitched around. And I'm just gonna open up Discord on my phone here and hope it doesn't turn itself off. You stay there. So DJ Devon three says, how do you figure out that a tape recorder could play back different speeds depending on voltage? Is that just a known thing? So this is a great question. If we, I'm gonna unplug this little Walkman here from the DAC and the QT Pi. And what I'll do is when I play, you'll see that this Walkman actually was designed as a dictation machine. And so it has a easily accessible potentiometer dial to change the speed. And this was usually used so that you could record notes and then when you wanted to type them in later, you could play it slower so that you could catch it. So this one, and you'll find a lot of them out there, it has an external speed controller. I'm just gonna zoom in here for a little bit so we can see things a little better. So you see here, variable speed playback. If you Google this, you can get these for about $15 on eBay. And this one, I didn't even have to change belts on. It was just working. If you do, you can buy a little pack of belts. This is the most common thing to be broken in a Walkman. This belt has deteriorated or turned to goo. Change that belt out and it's good as new. So if I play, I'm gonna play back this tone and let me turn off any effects. So that is what I recorded onto this tape. It's just a little sine wave chord. If I adjust the speed controller, you can even see this little pulley wheel goes faster as it's higher pitched. And it's gonna slow down. Now it's in sync with my shutter rate so it looks like it's almost wagon wheeling backwards. Okay, so that is on this somewhat special type of player. It's not too rare. The interesting thing though is here is a modern day very inexpensive, like $10 to $15 on Amazon type of player. It's called the Byron Statics. These are really cool. It's very similar to this old GE in that it has a speaker in the door. So you can play low quality audio right there. It has a microphone on it. So you record this one even has an AM radio in it. And it does not have an external speed controller but you can tell I'm leading the witness a little bit there by saying does not have an external one. And that is because when these types of devices are made they usually need some tuning with a trimmer pot at the factory before they go out the door. So someone is probably playing a tone a known let's say A440 on a tape and then adjusting an internal trimmer pot until it matches and then you know when you get it and you play your pre-purchase cassettes they're gonna be in the right key. So that trimmer pot is hidden right here. You just kinda have to search around for them a bit. So you'd go in there with like a long thin plastic screwdriver and just twist that to adjust the pitch. But since that has that even though it's not external it doesn't matter we can still go in and either add a potentiometer, a knob or set of knobs that's a popular way to do this type of hack or use either a digital potentiometer or a DAC digital to analog converter to send voltage and we'll hook up ground as well but to send voltage to that wiper so it's essentially a way to digitally adjust what that motor's voltage is and as that motor's voltage is adjusted it will change the playback speed. Generally I believe you're safe within three volts. Usually a little less is what you're gonna get from the adjustment wheel. So we can see on this one here let me try to move things and focus just a little bit better. Oh, we had it. There we go. Okay, so on this one this is the wheel right here so it's really easy to find. Let me grab a pointer. And so what I've done is I've gone in and soldered in a little cable with a connector pin on the end to ground and then I've got the essentially the wiper pin of the potentiometers connection here which is labeled on this one as VS plus which is I think variable speed plus that's what varies the speed of the motor. So if we take these and send different voltages to them anywhere from zero which means it should be unchanged from what this thing's default is up to I could probably do about three volts 3.3 volts with the QT Pi since it has three volt logic but what I'm doing actually right now is this little DAC it's a quad DAC chip that uses the MCP 4728 and it's connected to my QT Pi microcontroller there with a stem of QT cable. This has four DACs on it and so that means it can send four separate voltages so I connect ground right here and I connect that wiper variable voltage to the A voltage A out so there's ABC and D. It's possible there could be other things on here I would want a voltage control but probably not and I just happen to have this quad DAC you could use a single DAC you don't really need one this fancy and so let's go ahead and check it out. So what's going on is when I send MIDI notes from this keyboard here or from a computer or a sequencer any way you want when I send MIDI notes within a certain range that I determined is good to go so zero to about 28, 29 I think is the top MIDI note I'll allow I then convert those into little milli volt outputs for this DAC and let's go ahead and start the tape so let me rewind it a bit actually first okay so this is just droning on hopefully you can hear that well let me go check my my chat actually before I go any further to make sure people can hear and so this is a dry signal so this is just the sound of the tape going to this little amplifier over here and now when I press a key on my MIDI keyboard it is sending a command via this little USB hub to the QDPI so they're both being hosted as USB MIDI and then the QDPI says okay what MIDI note came in what should I change the DAC output value to so it's just changing that voltage that's on that center wiper of the motor controller now this is really responsive which is cool but since it's a physical device that has to ramp up it's not instant it's not some super quick stepper motor it's just a cheap little DC motor as far as I know we'll get some portamento or glide effect you hear woo when it gets up it goes down quick it can slow down faster than it can speed up you get that really cool and since this is MIDI and I'm terrible at playing the keyboard what I can do is I can create sequences with the sequencer of the keyboard or just send an arpeggio so that's what I'll do now I've got a little held arpeggio mode on here hit play and then I'll set it in ordered mode so whatever order I press keys and let go it's just gonna keep playing that little order of keys okay so now let me boost that volume a little I've got a quarter note time division based on the rate so I can just slow down that rate there I can adjust the subdivisions and check out how fast this will go this is incredible that this little motor is that responsive let's get a little confused by it you can almost make it act like a wavetable oscillator if you get going fast enough it'll start to become kind of its own funky harmonic tone so now let me go back to a slower speed on this and then I'm gonna do some little effects on it this adds some frequencies that this little amp isn't loving so let me I'm gonna turn off my AC for a second just so I can hear this a little better let me stop the arpeggio I'll show you the full range of this too let me change which is a little more of a reverb so I said this last week any of these type of tape things you do like so many things with music sound much better going through some reverb or other effects so I said I would show you the range let me take the effects out so that's the lowest this is sending zero voltage essentially and then we can go up through the little semitones I don't think I'm sending notes higher than that now this is just one choice of source material to use on this so let me let me hit stop on that for a second I'll take the effects out I can't remember what I have on the other side I think I have like a sawtooth wave so you can see I've just taken cassettes and recorded like 15 minutes or 30 minutes of something onto there or nothing in this case let's see there we go so oh where'd it go did I record over it? I might have let me let me at least let that play for a second it's gone now I've recorded over it so now what happens if we do take a look at some prerecorded stuff so here's a a mixed tape that's got like some depeche mode or something on it we'll get a copyright strike if we don't be careful but I'm sorry but I can't find the right things to say you know that song right alright so we'll stop there before we get arrested so yeah like I say I don't love that effect so much as just something prepared for this particularly to be a held tone sandwich drums they just sound like they've been yanked around a bit so that's the basic process though take a cassette record some long continuous tone last week I showed you can also make tape loops this one's falling apart which is the problem with tape loops they like to come undone you can make a tape loop oh good now it's a mobius strip so that's no good you can make a tape loop some people actually do that intentionally like double sided it doubles the length of this might be like 10 second loop or something with a twist in it it'll potentially I think you can record to both sides of it don't punish me if I'm wrong on that I might be wrong on that I've never tried that but these are pretty finicky these tend to ask a lot of a cheap walkman and they're easy some of them won't run when the second wheel is not in there I was just talking to Liz who's also working on some of these tape projects and she added back one of the little wheels into there and her walkman was happier to have something else to grab and spin but it's you know there's a cap stand roller that goes and grabs and twists here and it's not so easy this one I put a little rubber wheel made from a rubber band in there to try to give it some friction and maybe that's what it doesn't like but anyway that's a tape loop I don't necessarily need that for what I'm doing here because I can just record a continuous thing and it can have some character to it you could even put some shifts and changes and warbles in it or even some key changes or chord changes, root changes but the continuous one is a really great way to figure out what's going on with the cassette itself let's see what else so I've got this open right now for looking at it but what I wanna do ultimately is make this somewhat neat and contained so let me get this battery out that doesn't wanna come out so my DAC needs to plug into these two cables here so what I'm gonna do is see either if I can run those through an existing hole in here or if I have to drill I will this little battery compartment here zoom in again has a couple of gaps in it so if I feed these through here I was able to get these through and still use the battery which is nice you can also gain a bunch of space to put stuff if you wanna run this off of the DC power instead of battery which is nice because then you're not wasting batteries and it gives you all this space to put your electronics in so you could potentially just have the midi jack the USB jack for midi here and you could fit that cutie pie in that DAC in there no problem if I do wanna run this like that I don't think I can close the battery compartment all the way but I was able to get those batteries back into there and contacting that little spring and this will kinda go halfway down it basically closes my wires are a little thick there but if I go in and grab a couple screws get it most of the way closed couple other mods you can do on these there is the microphone input because this one's a dictation machine you can record onto it it has a little mic in so you could if you wanted to do your recording on here as well as your playback you could also do variable speed stuff while you're recording which is kinda funky you can hook up a little couple wires to where that mic is connected you might need to disconnect the wires or add a of the original mic or add a switch for that but then you could use an input of some kind I'm not sure what the level of it'll be and same with output I'm just using the headphone out on here some people like to get a line out that's not going through the little headphone amplifier so you can find I believe where these speakers are connected you could this little speaker here you could send a line out cable so it's lots of fun that can be had there with modding that but now with a little more put together I can reconnect to my DAC put a tape in there let's rewind a bit before I put the sine cord I just put a straight sine wave on there in the note of C and it was not as interesting sounding to me it didn't have enough character compared to putting the little cord on there that I put on and let's plug our headphone out nope, it's not responding what did I do wrong? would I break? you're still talking to that so you can see here I've got MIDI messages coming when this lights up let me just reboot the cutie pie by the way the cutie pie rather the DAC, this little DAC board it has a cool feature of a little E-prom on there that you can write a value so if you want to you can write a DAC output of zero so that doesn't change anything when it first boots up I don't mind it because it tells me that it's booted up but when it first goes to whatever note it's going to that's a preserved note or voltage output in the E-prom what did I break? broke something and it's interesting I don't think is that a connection here? let me set a I'm going to set a arpeggio playing so when it works we'll know so that's to ground it's still connected there oh you know what? let me just check the no that's just the potentiometer there what'd I do? this would be a good time actually to look at the output of this so what I'll do is let's unplug this and just bring this over to um the computer and I'll show you what it's what message is it's getting and how it's converting those to voltages so let me go to this little view here and let me find a usb-c cable set a weight on that cable so it doesn't fall uh and let's see if we open up the code on there make sure that's all still healthy nope let me unplug that metro m0 there it is and I'll open up a little serial connection to that true screen okay so um what I need to do is send usb midi messages to the qt pie and then we'll see what it does with those so in order to do that right now I'm just gonna in the background here I'm gonna launch vcv rack and tell it to send some notes out to the midi port on that this vcv rack to act as a usb host um let's see should I share that no I'm not gonna attempt to fade so let me just create a midi cc or cv to midi output device will be my qt pie and let's do a sequencer to that I think this will there we go so you can see from the output now I just have a sequencer that's sending the same note it's a midi note 60 so if I drop that down into the allowed range let me just set like four steps on here by default a lot of these vcv rack and other modular things have a uh 10 volt range it's a volt proactive so they'll send a huge range of notes out trying to get oh there was a 15 let me set this to one step okay so wow that's touchy yeah that's acting better okay so I'll send that and let me make a two note range okay so that works pretty well so now you can see I'll slow this tempo down as well uh when it receives the uh note midi note 15 that's sending 1.25 volts and when it's at 22 that's sending almost two 1.8 let me add one more note to the sequence and that'll send zero which is zero volts and then I'll add one more at the top of the range which I think if we look at my code here uh I am allowing up to 31 midi note 31 um this would be easier to dial in except I'm dialing in a voltage knob and not actual midi notes let me set the tempo higher there we go there's a 32 oh I've overshot it 39 35 32 still 32 31 there we go okay so that's my top that I'm saying 2.5 volts uh so let's take a look at how this works you can you can see it getting notes and then sending out those voltages over the DAC there uh and the way this works is I have the driver chip mcp 4728 for the quad DAC I'm importing that and I'm importing midi as well as midi note on and note off um and that is purely for listening so this is not sending midi out it is just receiving midi uh and then turning that into the DAC values so then I set up the uh stem of qt board there over i squared c uh instantiate the mcp 4728 and then I'm setting the DAC range to from 0 to 4095 uh then here's one of there's a couple ways to do the setup but I'm setting up this raw value as the maximum range there I'm using the internal reference uh and then I am uh setting that to a gain of 2 and so the internal reference is uh I think a 1 volt reference so I'm doubling that so I have a 2 volt reference against uh which I can control those those values pretty precisely I think this is also temperature compensated so um that's way more trouble than I should be going to for tape playback which is already a bit imprecise and and funky I think uh so I might try the other method which will give me the full 3.3 volt range uh then I have this uh each semitone is a 0833 volts which probably would work if I'm sending these out to a voltage controlled oscillator but for the tape thing I might need to mess with those numbers to get real semitones and just tune that by ear uh and then I have a little function I created here this midi to mille volt so it takes in a note a midi note like let's say note 10 and then that is the mille volts are 1000 times the note value times the volts per note which is the 0833 and that returns an integer uh why am I doing an integer I can't remember is that what I want yeah I don't really want mille volts I want the 12 bit value to come back uh this you can ignore this was just when I was testing I was sending it sending it some little melody uh I set up midi here which is standard midi setup for usb and then this is the main loop we listen for a message with this midi receive variable uh then if the message isn't none because that's a possible midi message to receive that a clock is ticking along but we're not getting any notes if the message is a note on type message based on how the library works uh I'm just printing it out note is this string conversion of that number uh and then if it is a a note that came in and it's less than 32 the range that I want to use 0 to 31 then I run that little function mille volts uh midi to mille volts and that gives me a message dot note or rather I'm inputting that note into it the output is what's printing down here and then that same value is what I'm sending over to the DAC so I think that's 12 bit 12 bit value rest here is just me messing around with other stuff so get rid of that and that's the basics of how it works so uh I don't know why I broke it but let me let me unplug this and go see if I can make it work again uh that's actually the first issue I've had with it once I got it working it's been pretty rock solid so let me let me see if I can maybe uh reboot some things here I'll turn off the keyboard and let's plug in the cutie pie plug in my and I'll open this back up if it's not working because maybe I just pinched it or something pinched the wires all right uh I'll play that now I'm gonna plug in the keyboard which shouldn't send any message just on its own and then this keyboard I've got to drop it down uh since it's just this sort of too octave range I've got to drop it down to the range that I want to use oh it's working now maybe was rebooting made things happy all right so there it is pretty neat uh pretty nice and neat closed up largely uh there and then I'll turn on some nice effects and I can put my mic over there I never asked if you could hear this very well oh something just ran out of batteries or happiness what just died I've angered something oh the the tape player finally ran out of batteries I knew this was gonna happen uh sorry about that let me yeah those are some double a's that have been going for a few days um and I've been doing a lot of rewinding which probably the motor doesn't love so let me connect back up here oh and I've got a weird sorry I got the wrong camera over here something just ran out of batteries or happiness that's the quote mr certainly all right so let's pull those out yeah this is why I really should put a three volt dc source in this what do I have I don't even know if I have any barrel jack to three volt um that would be a nice one to add Lamors been getting these usb c to power delivery voltages but I don't think three volts is is one of the allowed ones there oh it might not have been batteries it just ran out of tape it stopped maybe these batteries are still good that was just the tape coming to the end there and it wasn't obvious um one thing I could do on this just to make it a little cooler looking while I'm showing it off is remove the door uh usually you can get away without the door on these and then you can see what's going on with the tape a little better makes it a little more photogenic yeah that was that was all that happened there okay so let's show you what I go on here um this module here which is a effects digital dsp effects uh is being fed voltage from another one here which is a little voltage recorder called ephemera and that's just adjusting modulating one of the parameters but that'll sort of track the effect at least we'll track with the pitch which is neat you could of course also send midi to cv to these kinds of gizmos they're all living in the same world basically also a comment that I saw let me turn this down a bit and turn my ac back on so I don't melt um over in the discord someone I think Todd and okay you're on we're saying oh yeah since you got a quad DAC you could do polyphony you could have four tape decks play notes and have the uh midi hub send notes round robin style to each of the four DAC channels which is pretty cool so you could have sort of a type of polyphony um or parafony I think it would be polyphony based on having four DACs and a keyboard that's capable of sending multiple midi notes simultaneously uh which is really cool all right I'll stop that now I will stop the tape player so it doesn't just keep going but uh my assumption there was batteries and that was wrong and I think Todd by said it's hilarious that I'm adding fake dsp tape warble to his tape audio this tape player is not warbly enough I don't know what to tell you I mean I could probably do that in code by sending uh like a little low frequency oscillation instead of telling the DAC to send a locked in note we could probably have a little fluttery thing that'd be kind of cool let's add flutter and wow flutter and wow uh very cool so anyway thanks for uh for hanging out and allowing me to dive into some tape stuff it's loads and loads of fun uh you can generally speaking pick up one of these cheap players I'll show you I don't know if I showed a link to this but the one that I'm using um is let me just look for g e three five three six two tape player looks like that right there uh you can find them in ebay or is one for 20 bucks I think I got mine for 15 or something like that or maybe even 10 I think I did an offer I just look for ones that say they work they've been tested in work or uh if you want to try your hand at the um modern more recently manufactured one which I'll do I'll tackle next uh that is the Byron statics right there if you google around for this there are quite a few people online who've been doing some neat hacks with this um and I'll put some credits to some people whose work I've I've checked out I'm forgetting I'm blanking on names right now but there's a few people have done some cool hacks with this including um one maker who hacked that little micro usb port off of the circuit board and or hacked it tapped into it to run the qt pie put a qt pie in a DAC or a digital potentiometer in there where the batteries were uh and I think maybe powered yeah powered all of usb as well as the qt pie which is cool um and my apologies for forgetting names right now but I'm still slightly jet lagged that's my excuse all right um I think that's going to do it for today so thanks for stopping by over in the youtube as well as in our um discord chat and I will be finishing up an article or a learn guide on my eight by eight midi neo trellis and then I'll be doing a guide uh collaborating with Liz on a couple of ways to do some of this tape tape hacks um let's see Dexter said what if we did a one-off community project box with all in stock components what's that in reference to the tape thing something else not sure all right thanks everyone for stopping by for eight of fruit industries this has been john park's workshop i'm john park see you next time bye lars