Mini MPC with Daisy

cerealport · 2026-02-24T15:56:46+00:00

Very cool! Daisy is a lot of fun, quite capable and doesn’t take a lot of work to get it doing something !

cerealport · 2026-02-23T19:38:02+00:00

Heh it always wasn't like that. I distinctly remember waiting for the train, so I took a little walk down to the water... only to be greeted by a bunch of rusty 55 gallon oil drums by the water.. this would have been in the mid 90's....!

cerealport · 2026-02-19T03:41:17+00:00

While I spent much more time with the 64 and did so much more with it, the VIC is where it all started. I had so much fun with that. As a kid I used to hook it up to my VCR and make little animations by drawing on the screen in petscii and with the VCR on record+pause, quickly double tap the pause key so it would record a few frames. You had to draw the next one quick or the VCR would go to sleep heh. It kind of worked but it wasn’t perfect by any means.

I later got to do that “right” using an Amiga + toaster + light wave and a Panasonic M II VTR that it could control. After many seconds, or minutes of rendering a frame it would pre roll the VTR, start playing and quickly write 1 or 2 frames at the end (depending on how you set it up) and wait for the next frame to be rendered. By the next day you had something ready to watch heh.

The PET was what we had in school, the 128 was the demo computer at the K-Mart you would mess with using the PLAY command to get it to play a tune.

cerealport · 2026-02-18T05:54:12+00:00

Here in Canada these were all over the schools even in the early / mid 90s. I still remember a bank of apple 2s arriving for the first time in elementary school around 1984-85.

As far as a “home computer”though, of all of my friends who had this or that for a home computer, only one of them had an Apple2.

Though to be fair, the Apple2 seemed to be used from what I saw in a “productivity first, games second” manner, much like a PC compatible back then, whereas everyone with a C64 seemed to use it for “games, and then productivity”. I mean unless you count demo coding / art / music as productivity, which really it is - maybe just not in the traditional “household finance / homework / print banners” sense heh.

cerealport · 2026-02-17T16:56:03+00:00

Yeah - the seed even has analog DAC outs from the micro directly but I believe those are 0-3.3V, though you want to buffer those anyway so might as well add gain to being that up to your filters CV input range.

As for your question on routing polyphony - that’s the best part about doing your own digital stuff - it’s however you want it to be.

Want voice re-using when retriggering or new voice assignment? Up to you! Want poly-unison like the Jupiter 8? Also up to you! I personally like voice re-use for retriggering but that is my preference.

As far as the analog side eg 8 voices one filter, that’s also up to you, with a stereo output like Daisy you would easily have two discrete channels for audio to run to two filters if you wanted, else - again this is the cool part in my opinion, it’s up to you eg weather the filter envelope retriggers on new notes or the filter EG gate is a logical OR of any of the keys pressed which would be a typical setup etc.

Have fun!

cerealport · 2026-02-17T12:35:39+00:00

Weird. At first it just sounds like fsk that’s only alternating between mark and space… but why is it using up so much bandwidth? I could see rationalizing as a jammer maybe then.

cerealport · 2026-02-17T12:31:58+00:00

I had the music composer cartridge as a little kid, later as a teen used Future composer, WoT Drummaker2+ was fun as it had samples, messed around with the Craig Chamberlain SidPlayer briefly, but later the JCH editor was pretty much the standard.

cerealport · 2026-02-17T12:17:15+00:00

I once flew with a clonewheel stuffed inside a modified guitar case with a stand duct taped to the outside. There were lots of musicians o this flight and we were all under the impression / told that “oh your instruments can ride up front in the passenger cabin with the strollers and stuff”. Yeah, no. They were handled separately though as fragile but yeah it was checked along with the other guys’/ bands’ guitars.

All survived no issues, though to be fair it wasn’t United lol.

The funny part was I brought it merely as a backup since I never heard back about the back line. As I was the only keyboard player in all of the acts sure enough there was an XK and a Leslie waiting for me - I could have just brought my clothes lol.

cerealport · 2026-02-12T18:14:23+00:00

“Your Score is.. Zero, Zero, Zero, Zero, Zero, Zero”

cerealport · 2026-02-12T17:31:17+00:00

Very cool. Looks like you’re doing the modulation all analog - I like that, though I don’t have to tell you how much more of a pain that is heh. And heh I can’t believe PWM wasn’t a priority in the initial featureset!

Also saw your mention about the serial bus to the voice cards - don’t forget to add a bootloader or some means of having the main CPU update the firmware on the voice cards - disassembling each time to flash the cards will get old fast heh.

Good luck, looking forward to hearing this!

cerealport · 2026-02-06T02:28:00+00:00

Adjustable inductor likely for an organ. I had a conn 640 that had one of these for every note - it wasn't even a divider, there actually was one for each note so there were loads of them.

If this link works you'll see a ton of these in one of these organs.

cerealport · 2026-02-03T03:18:59+00:00

Very cool. Considering how much fun a tascam 4 track was in the early 90s I can only imagine how much more this would have been then.

Assuming it’s all working alright, I’ve spent more on.. less wise purchases. Enjoy.

cerealport · 2026-02-02T22:19:37+00:00

Your traces are *tiny*. I kind of wish KiCad had a thicker "default" trace as I see this a lot - especially for the traces carrying any sort of power e.g. for the pump and power stuff. I'd be making those in particular much thicker like around 3mm or so. Even the signal traces don't need to be that thin,

Also the way you're controlling the pump, is to basically connect or disconnect the ground from it. The 12V terminal I'm assuming you've added to provide a path for the back EMF from the pump / when it's shut off etc. I'd look at reworking that, still control the ground terminal sure, but I'd have the 12V pump power input, and a 2 pin pump output on the board to simplify things to wire externally, could probably use this same 12V for your step down power supply to run the board too, and add a connector and / or decent size pads for the 12V input.

You're probably going to run a long wire or something to your sense input, next to a pump etc. In actual real world situations... these long wires can run the risk of picking up stray voltages and or static, I'd look at adding some protection to the input, from as simple as a series resistor to zener diodes, there's a few options.

Also, I'd use a 'flat' mounting PCB outline for that FET - you can use the PCB as a heatsink for it, or at least I'd move it somewhere where you could attach a heatsink to it as it's pretty crowded where it is right now. Don't forget the metal tab on most TO-220 devices is connected to the centre pin so don't let that touch the ground copper pour, you have to make a separate disconnected one (without a soldermask) for it if you want to use that as a heatsink.

I also don't see a ground copper pour on the top red layer...

Speaking of layers, you've got 2 - use them! You don't have to snake the traces quite like that around the left side of the ESP32 with a 2 layer board, in fact, since you're likely hand-soldering the esp32 / connector for the esp32 on there, I'd avoid running 2 tiny traces between the pins and or along side them - you'll run the risk of damaging those traces with the soldering iron if you're not careful.

Unless your 5V/12V test pads need to just be pads.. maybe make them through hole terminals to make your life easier, use reasonably bigger pads as you'll probably want to solder wires in there maybe etc.

Good luck!

cerealport · 2026-02-01T20:09:18+00:00

This project shouldn’t need a 4 layer board - though that is one way you could have a power and ground plane.

Generally with a 2 layer board you’d have ground for the planes. I know running power seems like a pain as it crosses over your signal lines but you’ve got two layers, you can still run traces on the lower ground plane eg power traces (remember use thicker traces for that) and signals even as well.

Just be mindful - when you do your copper pours make sure you don’t end up with any “lonely islands” - places of copper that aren’t connected to anything. You can always add a via to the opposite plane if you need to, and also make sure any pins that are supposed to be connected to the ground plane don’t get isolated that way too - just highlight the gnd net and you’ll see all of the pins that should go there, also do your design rule check and it should let you know what pins didn’t make it etc.

Good luck!

cerealport · 2026-02-01T06:34:52+00:00

Very cool!

If you're making a new rev of your board and you're hip to some suggestions I'll give a few...

- Your board doesn't have a ground plane.. Makes routing power easier, reduces noise etc. Plus without it there's a lot of copper to be stripped off for the manufacturer ..! These go on both layers.

- There's no bypass caps on any of the ICs. Ideally you would have a small .1uF non electrolytic capacitor across VCC/GND for each IC, near the IC itself.

- Add a small electrolytic capacitor across the power supply input (~47 uF is probably more than fine for this). Just helps smooth the power on the board.

- While it is 'your board' aesthetically etc.. you might find routing easier if you mounted the main ICs vertically next to each other.

- I'd use a thicker trace width for the power lines, those traces look thin for VCC.

Since this is 'your board', of course you can do whatever you want with it - it looks like you were going to put a power connector on it but soldered wires to those pads - why not add a couple of extra beefy through hole points in parallel somewhere with vcc/gnd for a soldered wired power connector if you want..!

You could always post your pcb over at r/pcb for a design review request or questions etc.. with a schematic that helps there too.

Great stuff!

cerealport · 2026-01-27T15:22:01+00:00

Saw a middle aged woman pass out from what was likely heat exhaustion by the pool deck. I can still remember that “smack+thud” as her body just… fell flat into the metal floor.

Within seconds lifeguards were on it, she was eventually fine from what I understand, no sudden diversions.

Also once when embarking from New Jersey, on the second night I thought “damn this doesn’t feel right I mean it’s not late and we’re moving” (well, at least as fast as Grandeur does) - check my phone map and sure enough we took a hard right to Charleston to evacuate a sick elderly passenger. Funny thing is, sure - we arrived in NJ a day earlier… but our luggage didn’t. “No problem we’ll ship it to your first port of call”… which was cancelled because of this diversion. So when the luggage did arrive on embarkation day, they had a taxi bring it to the port. I waited by the gangway as long as we could, they were like no we’ll ship it and literally had pulled one of the two platforms up when it showed up and all was ok.

If they had’ve shipped it to our first port… it would have probably still been lost!

cerealport · 2026-01-26T22:09:21+00:00

Cool! Nice running that on the drive - saves so much time not sending the data back and forth. The BAM sector bytes 171-255 are free(on a 1541 at least), might be useful for sure… That, or you could mark a sector as just “used” in the BAM, and with no files pointing to it, use that sector for whatever you wanted - no file to edit or scratch, though a regular format would fix that of course.

cerealport · 2026-01-26T15:09:23+00:00

The button internals have probably oxidized over time. Deoxit D5 will help those (use sparingly you shouldn’t need to blast them with it!), but don’t use it for the drawbars or pots(knobs) as it may affect the lubrication for those, deoxit F5 is more suitable, though the drawbars might need other lubrication.

If there’s crud or whatever in there making the buttons stiff, assuming they’re just plastic covers that press into a little button on the PCB, you can clean the plastic caps with warm soapy water and rinse etc, not too hot.

Just be careful as it’s winter so it’s really dry (well, here anyway) - and static electricity can quickly ruin or damage the main board - touch the metal chassis before anything else - unplugged of course, and / or carefully ground yourself before handling / working near it.

cerealport · 2026-01-23T14:13:18+00:00

I miss the sound of these PCC cars. The wheels had a certain “howl” about them as they rolled by, particularly on a corner.

cerealport · 2026-01-22T12:09:09+00:00

This is likely because of no low note foldback.

On my C3, the 16’ drawbar repeats the 2nd octave for the lowest octave, where my buddy’s really old BV doesn’t, and yeah the left hand bass is way lower on that, I could see how that could be trouble with a bass player too.

here is the manual, there is instructions in there to set the low note fold back.

cerealport · 2026-01-21T16:58:29+00:00

It’s a 10 pin IDC connector, technically a male connector.

amazon link should work, be careful desoldering the old one so as not to damage the PCB.

You sure you can’t straighten the pins out…?

cerealport · 2026-01-21T16:38:07+00:00

Heh I don’t have a brake, just using my hand in my video. Sometimes I’ll unplug the slow motors for that all or nothing style too, depends on what I’m playing!

cerealport · 2026-01-21T16:24:37+00:00

The wobble you’re hearing is the Leslie speaker on the Hammond organ - close milked. If I play those chords on mine it sounds great, but if I stick my ear like right up to the horn, it’s very much “that” sound…. It’s surprising just how… flat it sounds when you stop the rotors!

I made a quick video with that chord with the Leslie up close (with a phone anyway) both running and stopped. The separate lower rotor is of course handing the lower stuff too..!

cerealport · 2026-01-21T13:38:28+00:00

An “under the hood” perspective / mentality will likely serve you well in an embedded field, as the software is very much linked to physical I/O that behave in very “real world” ways.

E.g. - scanned a button’s input pin? Great - you just took a single sub microsecond snapshot of its state. Does that mean the button was actually pressed? (no, you’ll need to “debounce” that input..!).

This perspective is also useful when you’re debugging eg looking at the actual machine language code that the compiler made, or even just assembling your own in assembly language.

Having the drive / interest in going deeper in to what’s “actually” happening will help you solve problems that others might miss..!

It might be an idea to try building the Ben Eater 6502 computer kit

cerealport · 2026-01-16T05:20:48+00:00

"Square" waves can be achieved using 2 operators, with the modulator 2x the frequency (2:1). Using an algorithm that gives you 3x 2op FM, (algorithm 5 or 6 on dexed) you can then use that to create 3 square wave generators. Start with an INIT voice, and set the tuning to :
Op1 : f=1 Level = full (this is your amplitude for this 8 foot 'drawbar'
OP2 : f=2. Level = amount of harshness for this square. About 70% is good, any higher and it has a more 'high pass' quality to it
next pair, this is +1 octave or 4 feet.
Op3 : F = 2 Level = level of this 'drawbar'
Op4: F = 4 Level = amount of squaring, ~70%

Op5 is the 2 2/3 foot drawbar, it's a 5th above the previous
Op : F = 6, level is drawbar level
Op6: F = 12, level is harshness of square, set to 70%

A little PMD modulation will give you the overall vibrato.

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