POWER to the People

Here's a module that's got +12V, -12V, optional +5V, and a headphone amp. It charges via USB-C, and seems to work pretty well... my multimeter shows confusing numbers when I try to measure millamps, hopefully some actual stats will be forthcoming.

So here's the placeholder for the build document. I'll hurl some

 SAFETY WARNINGS

 here because lithium ion batteries can be hazardous.

• Never short a lithium ion battery. They will die, possibly by bursting, possibly by lighting on fire. They are very difficult to extinguish, since they often have oxidizing chemicals built in, as though they're DESIGNED to be rocket fuel or something.
• If you do have a battery light on fire, put it in a bucket of sand and move the bucket to a well-ventilated area. Wait for the battery to stop being on fire. Wait even longer for it to cool. Then take the goo to a qualified battery disposal site in your area.
• Pay extremely close attention to the polarity of the battery you're plugging in to this module, and the polarity of the pads or connectors you're connecting to. I can't guarantee that your battery will be correctly labeled or built, so please check that stuff. This module has reverse-polarity protection, but try not to test it.
• Avoid shorting the outputs rail-to-ground, or rail-to-rail. The module is built with short-circuit and over-current protection, but again, try not to test it.
• Use boxed-style IDC headers for the Eurorack cable headers. This is important because you don't want to plug your cables in wrong, but even more importantly, they'll provide the physical foundation for the cable ends that the 13650 battery you might be zip-tying to your module. This module will work with any single (1S, in battery lingo) lithium ion battery, but there's holes to make it easy to zip-tie a cylindrical cell there.
• Please secure whatever battery you use in a safe way inside whatever enclosure this module will live in. Lithium ion batteries should never be rattling around inside anything, so seriously, folks, don't goof around with this stuff.

Features of the M4TM POWER to the People

• Rechargeable and portable bipolar power for Eurorack modules
• Optional 5V power rail 
• ? mA of power with ? voltage sag ??
• Overcharge, undercharge, overcurrent, and short-circuit protection
• Headphone amplifier! Stereo, with the top input sending signal to both channels if nothing is plugged in to the bottom input
• The cheapest battery-capable +/-12V power supplies out there will abuse the battery if you charge the battery while using it. This one has a little mosfet that allows for use WHILE charging. Neat.

Okay that's it for now. I'll probably make a build-guide which will hopefully be here, or at least I'll link to it. 

Juanito's Sweat Factory

 Hey everybody, this is basically a placeholder.

I'm developing a CV sequencer module! Four inputs with knobs, for parameters. Eight CV knobs for, like, setting the CV of each step. One button in the middle. Oh yeah, two buttons under the top left and right pots, y'know, like HorseDebt. Eight outputs, one Pure DAC analog, three PWM analog, four digital but there's spots on the PCB to add a capacitor for smoothing if you wanna write firmware that can put out more PWM signals.

EXCITING THING: this is a radically flexible module. At its heart is a AVR128DB64 chip, which can be coded in the approachable Arduino IDE, and there's even gonna be a USB jack right on the PCB so all  you need is this module, a USB cable, and a computer, and you'll set to program this little guy??????

I haven't even started writing code for this, but it's gonna be flashy, it's gonna be flexible, and it's gonna have TWELVE JuanitoPots with addressable LEDs under them. BlinkyFlashyBloopyFun

FZilter featuring a MB87186 chip

 

A mysterious forest wizard shot an arrow into a nearby tree trunk with a message wrapped around the shaft. It said "Wouldst thou deign to design a PCB for an exotic precious gem of a microchyppe which one canst obtaineth not except by exxtraction from a Casio FZ-1 or symilar keyboarde?" so I stuffed a message in a bottle saying "heck yes" and threw it on the water.

I had never heard of this chip or the fact that you can build it into a Eurorack module, but it's quite a unique thing. The chip is a "digitally" controlled filter and amplifier, which garnered some praise back when it was new for sounding analog. Turns out it IS more-or-less analog, with a switched-capacitor filter and hmm, I'm not sure how the audio amplifier is managed.

What is a switched-capacitor filter?????? Glad you asked. A filter is almost always a capacitor-resistor situation. A resistor reduces how much current can flow, and a capacitor can be thought of as a kind of balloon which "fills up" when a current flows into or out of it. Most synthesizers vary the resistance (sort of) to adjust the frequency at which a filter takes effect. You can do this with a potentiometer, which you need to turn with your hand like a cave man (ugh) or you can use a voltage-controlled resistive part like a Vactrol or an OTA which stands for operational transconductance amplifier obviously but just understand that it's MUCH easier to use a voltage to adjust the "resistance" section of a resistor/capacitor filter than adjusting the capacitor.

Acute cholecystitis and biliary pancreatitis also uBraids

 

You heard what I said. Acute cholecystitis and biliary pancreatitis.

Cholycystis is the fancy word for gallbladder, "gall" being bile, or the "coleric" humor in the old Humorism concept of human health. Gotta have those humors in balance, right?

Biliary pancreatitis is where your pancreas gets irritated, inflamed, basically super pissed off. The pancreas is the chemical plant of the body, it makes insulin, pancreatic polypeptide (????) and something called pancreatic juice.

Why "juice"? I don't think of "juice" as a medical term. I guess it is though.

What happened? Well, my gallbladder filled up with stones, and from time to time, one of them got passed through my Main Bile Duct, and when it was a difficult passage, it made me feel gross. My tummy would hurt and my pancreas (I know now) would get upset and hurt as well.

A gall stone got stuck in that main bile duct sometime before Christmas Eve, causing my whole digestive tract to give up, shut down, say "NOPE" as clearly as possible, so anything I ate or drank came back up the way it went down (except much more unpleasantly.)

I got more and more uncomfortable, until my wife drove me to the emergency room and they admitted me to the hospital, calmed my extremely intense pain down with opiates, palpated my abdomen, gave me two IV antibiotics as a preventative (?????), passed my torso through the opening of a CT machine, and declared that I would need my gallbladder yeeted into the biohazard bin.

I asked so many times if I could keep my extracted gallbladder but everybody said no. I wanted to make it into a hacky-sack. Turns out though, the "stones" aren't actually mineral stones, they're made of cholesterol or bilirubin or blood ewwww and I bet it smells bad, so I'm okay with them just throwing it away.

It was big, though. I have a "four inch" (less than three inch real measurement) incision right below my lower right rib cage where they had to pull out the gallbladder.

The pain before and after the surgery was intense. Worst pain of my life before, even worse pain after. Somebody mentioned within my earshot post-surgery that my uncomfortably bloated abdominal cavity was filled with "a straw-colored fluid" which (in my imagination) became pancreatic juices and enzymes eagerly trying to digest my liver, intestines, bladder, kidneys... as though somebody had inflated the muscle/skin balloon surrounding my guts (this happened -- they use carbon dioxide gas) and rubbed Frank's Red Hot all over my entrails. Ow ow ow ow. Plus, the bloating was severe and got worse, making it impossible to take full breaths.

Well anyway, that was two weeks ago. I'm weak, skinny, exhausted, but basically pain-free using OTC pain meds (severe family history of opiate abuse so No Thanks, Prescription Painkillers!) and as of today I'm allowed to lift more than 20 pounds (9.071847 kilograms exactly) so I can get myself back in shape.

Some of you will have donated to my "Fix Juanito's Tum-Tum" fundraiser to help pay medical expenses, and for that, thank you so so much. Mutual aid is a grimly heartwarming bandaid for our extremely broken, abusive system of paying for medical care. Thank you again.

HungryFuzz HEY GUYS, new module!

NEW MODULE TIME! Well, prototype time. The design is done, and there's some germanium transistors that will be going in there, and they need testing. So here's the rundown of the module and circuit, and if you're looking for build tips, those are after the break!

I like distorted kicks. It's part of my identity. Both modules in my Hungry- series work so well with kicks, the HungryRat (Proco Rat clone) is HARSH SHARP, and my HungryThumb is a compressor and does amazing things to kick drums, including soft clipping, compressing, saturation, lots of fun. Well, I don't know how many germanium transistor distortion pedals have been ported to Eurorack, but the number is probably low (germanium transistors aren't common) so here we go!

The original Fuzz Face pedal "remains an enigma". It was released in 1966, consists of a battery, four resistors, three capacitors, two germanium transistors, and two potentiometers. Ludicrously simple!  The page I just linked to talks about how some of the unique sound may have been a happy accident. There's asymmetrical clipping which starts out soft and goes harder with increased signal voltage. I think that's probably the main accident?

The design has been developed exhaustively over the years, with different designers experimenting with different transistors and transistor types (NPN silicon transistors, for instance), and tweaking resistor values, and (my favorite) hurling potentiometers in there wherever they might make a difference in the sound.

For pedals, where the knobs are in the stompbox which is usually on the floor, two knobs may be fine. But we synthesizer guys love to have all the knobs at our fingertips, and the Zvex Fuzz Factory seems to be the most complex design out there, with five whole knobs to play with. So I cribbed from that circuit, added my starve circuit which also allows the distortion core to work with bipolar voltages (so there's no DC swing when adjusting the starve, right?) (although I left the DC blocking capacitors in the signal path) (which are MLCC in the prototype because I don't believe that most capacitors "sound" like anything). There's a stupidly wonderful tone control in there, and of course a proper output buffer with adjustable gain to get the output to be a nice safe 1K impedance at 10V peak to peak.

And that's the circut! I have zero zero zero hands-on experience with a Fuzz Face of any variety, so I'm.... excited to see how the prototype sounds?

But I'm neglecting to talk about germanium transistors! They're nifty! And very obsolete. So check after the break for what to do with these weird parts!

I went microViral?

View this post on Instagram

A post shared by Juanito (@juanitohm)

 Okay um, I hope that worked...

I got to play a short set with my mostly-working tin can synth a couple days ago! This video was taken the night before, and as of this post, has 6.8K likes. Wow! I shall keep my head only as overlarge as it already is (I have a healthy ego) and only halfheartedly attempt to chase further likes and views. Y'know, by replying to Instagram DMs and answering questions in the comments.

Playing my tin can synth (Hello Kitty Furiosa is her name) was a TON of fun, and prompted two ideas for modules. One of my tin cans has eight knobs, three switches, a NINTH knob, a clock input and a CV output. I think the three switches are a binary number select bank (eight options) and the ninth knob is a "sequence length" selector. Mode 0B000 (all switches off) is probably a sequence of CVs that go from knob 1 to knob 8 (or less far, depending on the ninth knob). Mode 0B001 is probably "cylon" or "KITT from Nightrider flashy lights mode" that go back and forth. Modes 0B010 through 0B111 are utter mysteries to me, and are probably melody or bass lines from popular songs like Billy Jean or Part Time Lover. The theory being, if you happen to tune the CV knobs correctly, your VCO will play the desired tune, which is the strategy I used for my main CV sequencer (12 knobs actually 24 thumb-wheels with coarse and fine tune per CV step) and I have never once managed to get anything resembling Stayin' Alive (etc) out of them. BUT! The patterns remain compelling when the CVs are tuned to other notes, harmonious or un.

My second idea is a "YOI" module, which is inspired by my tin can synth lacking a sample rate reducer AKA fast sample/hold. Those sweet and mysterious YOI sounds that litter dubstep/DnB tracks like empty alcohol containers litter the floor of a dubstep/DnB venue floor can be gotten with a simple VCF (don't be shy with the resonance) and a sample/hold module. The interaction of the VCF cutoff frequency and the frequency of the S/H makes a YOI and I love it so much and don't really understand how those two things make that sound. My NyquistNightmare can sorta do YOI sounds, but a dedicated YOI module would be neat :D

Okay, that's all. I also had a cold the past few days, so my viral post went unnoticed for many many hours while I slept or read or otherwise ignored the internet. And ignoring the internet is always a good call.

DuckMixer NEW VERSION!

 I ran out of DuckMixer front panels! I'm not sure how -- did I order fewer panels than PCBs? Maybe? But because of that, I embarked on ordering more of each!

Adding new features and tweaking footprints is a great thing to do when sending out for new PCBs, and the DuckMixer had holes for the jack LEDs that were just a bit too large for the 1206 LEDs, allowing them to slip through a bit. One of the jacks was flipped 180 degrees from where it was supposed to sit, making it press up against a potentiometer.

So I messed with all that.