Do it yourself crew in the house?

First test of the Rollz-5 and everything seems to be working as it should. Not sure what's causing the high-pitched whine - maybe one of the ultrasound filters so I need to investigate there...

edit: the 12V wall-wart I was causing the whine.  A 9V one powers it silently.

The front+rear acrylic panels I designed should be here Monday Wed. 

This morning before work I realized the only thing I need to build one of these that I don't already have is a $20 screen (assuming I can find the USB keypad I got back in 2012 to make it easier to edit on a laptop and then hardly used before the laptop died spectacularly).

So tight right now that I can't afford it but I get paid in a few days.

EDIT: of course part of me wants to get this for it:

https://www.ebay.com/itm/iKey-PM-18-USB-Nema-Stainless-4X-Panelmount-Numeric-Keypad/143516587897

If I could afford it I probably would because that's actually a really low price, they retail for almost 5x that. Fortunately I'm too broke and the rubber coating on the keys looks nasty to use anyhow.  It would probably suck for this job, it's just stylish.

This thing is fucking great

I really want to separate the outputs for better volume control and FX on individual voices.

I need to get it running into the Octatrack for some great samples.

I was getting in a good rhythm over the last week - did a NLC 8-Bit Cipher and it went pretty smoothly, feeling like I'm getting alright at hand-soldering SMT, at least 0805. Then I tried to do a Veils today and phew, it was a disaster. I plugged it in and I'm getting Christmas lights but no sound. At least it looks pretty. I'll have to go hunt down shorts tomorrow, I guess. I think I'm gonna stick with thru-hole and 0805 for now until I take the plunge and get an oven.

  On 7/13/2020 at 3:25 AM, sweepstakes said:

I was getting in a good rhythm over the last week - did a NLC 8-Bit Cipher and it went pretty smoothly, feeling like I'm getting alright at hand-soldering SMT, at least 0805. Then I tried to do a Veils today and phew, it was a disaster. I plugged it in and I'm getting Christmas lights but no sound. At least it looks pretty. I'll have to go hunt down shorts tomorrow, I guess. I think I'm gonna stick with thru-hole and 0805 for now until I take the plunge and get an oven.

I have a cheapo "858D" hot air station I use for all my SMD stuff.  I never tried building SMD w/ an iron as I knew I was going to fully jump in and wanted to make it easy on myself.

There's lots of different brands, but they're all labeled 858D

  On 7/13/2020 at 6:16 AM, Hautlle said:

I have a cheapo "858D" hot air station I use for all my SMD stuff.  I never tried building SMD w/ an iron as I knew I was going to fully jump in and wanted to make it easy on myself.

 

There's lots of different brands, but they're all labeled 858D

 

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Cheers, that looks way less bulky than what I had in mind!

  On 7/13/2020 at 6:16 AM, Hautlle said:

I have a cheapo "858D" hot air station I use for all my SMD stuff.  I never tried building SMD w/ an iron as I knew I was going to fully jump in and wanted to make it easy on myself.

 

There's lots of different brands, but they're all labeled 858D

 

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I've got to say, I've had a similar cheap rework station for years and it's been at least a year since I used it (and when I did it was for shrink tube) because I've come to realize that using the same old Weller with a narrow chisel tip that I use for everything else is a lot easier for SMT than hot air was. Only difference is when I do SMT I usually use a flux pen.

Ugh. I unsoldered all the pots and found some shorts in the TSSOP14 OPA1654. But the pins are so fucking tiny that I can't even tell whether they're connected. I guess by being pulled onto the board by the corner pins, that pressure might be enough to make contact? I plugged the module in without the pots and I got the same arrangement of Christmas lights; obviously didn't test sound because I assume the pots are needed for that.

I will really have to get astronomically lucky to properly solder this with my old Weller because I just can't properly solder anything but the corner pins even with 0.3mm solder. I don't know whether this is a job for the 858D but I'm guessing it could only have better luck. It's those 4 fuckers on the left, between and slightly below the pots.

This is gonna be a real adventure. I think this is gonna be my last MI until I level up a bit. I went through this with the Shruthi too, although back then it was because I was a total soldering noob.  Fortunately I don't really want anything else of hers at the moment, heh. The only things I really want for now are a couple more clock/logic/sequencing options and VCAs/mixers (though if I can get this Veils working I might be covered there). Maybe a delay. NLC has been good to me so far, so that's probably what I'll do for those.

Next up, learn how to remap keys so I can use it with the temporary keypad until I decide on a permanent one.

EDIT: of course none of these custom installs have a FAT formatted bot partition like a stock install, and I don't have Linux installed on anything and working on the RPi itself is kind of a hassle because of the way everything's set up, so remapping keys means digging out an old laptop and either booting from a Knoppix CD or going all in and doing a full Linux install.  Leaning toward the latter but I have a couple hours to decide before the boot partition is backed up. Seems like n real choice, though, it's always good to have a Linux machine of some kind handy when you need it.

Just watched the first two parts of a series on building a V/oct VCO from scratch. It’s really basic, but really good. I learned a lot.

https://www.youtube.com/watch?v=QBatvo8bCa4

He explains how an oscillator works and, in part 2, how you control the pitch.

Panels arrived for the Rollz5 and it's looking sexy
 

  On 7/18/2020 at 10:06 PM, rhmilo said:

Just watched the first two parts of a series on building a V/oct VCO from scratch. It’s really basic, but really good. I learned a lot.

https://www.youtube.com/watch?v=QBatvo8bCa4

 

He explains how an oscillator works and, in part 2, how you control the pitch.

 

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Good one!  I've watched a bunch of the Modular In a Week guy but I'd never seen this guy.

  On 7/18/2020 at 10:06 PM, rhmilo said:

Just watched the first two parts of a series on building a V/oct VCO from scratch. It’s really basic, but really good. I learned a lot.

https://www.youtube.com/watch?v=QBatvo8bCa4

 

He explains how an oscillator works and, in part 2, how you control the pitch.

This is fantastic, thank you!

Somewhat related - I watched this a few days ago and also learned a lot

  On 7/19/2020 at 8:05 PM, sweepstakes said:

Somewhat related - I watched this a few days ago and also learned a lot

 

Just watched it. Thanks! Bookmarked!

  On 7/14/2020 at 5:22 PM, TubularCorporation said:

Next up, learn how to remap keys so I can use it with the temporary keypad until I decide on a permanent one.

 

EDIT: of course none of these custom installs have a FAT formatted bot partition like a stock install, and I don't have Linux installed on anything and working on the RPi itself is kind of a hassle because of the way everything's set up, so remapping keys means digging out an old laptop and either booting from a Knoppix CD or going all in and doing a full Linux install.  Leaning toward the latter but I have a couple hours to decide before the boot partition is backed up. Seems like n real choice, though, it's always good to have a Linux machine of some kind handy when you need it.

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Why do you need a FAT formatted boot partition? Got to be some easier way to remap the keys, especially if it is just for one application.

I was digging around and found a cache of ICs from 2011. For some bizarre reason I ordered 3 different sizes of Atmel EEPROM - I think I was thinking of auxiliary ATTiny memory? I've never worked with this stuff before but I'm wondering what I can do with it. Maybe make a sequencer or something.

Also there were a bunch of optocouplers. I guess you can make (passive?) VCAs with these - I was looking at Mystic Circuits' design and wondering if I could roll my own. I have 6-pin and 8-pin varieties though. Here's some more info on that: http://siryoa.blogspot.com/2013/07/transistor-output-optocouplers-for.html

  On 7/21/2020 at 4:56 PM, thawkins said:

Why do you need a FAT formatted boot partition? Got to be some easier way to remap the keys, especially if it is just for one application.

I didn't. It was easy. I was just being lazy.

  On 7/21/2020 at 5:13 PM, sweepstakes said:

Also there were a bunch of optocouplers. I guess you can make (passive?) VCAs with these - I was looking at Mystic Circuits' design and wondering if I could roll my own. I have 6-pin and 8-pin varieties though. Here's some more info on that: http://siryoa.blogspot.com/2013/07/transistor-output-optocouplers-for.html

Hey, thanks for that link! I recently came into (ie bought) a couple of optocouplers for that exact purpose (well, I was going for active, but still). Now I can read up on how to go about it.

Sure thing! I just tested it with a 4N28 and a 100K pot with a 5V source, and it seems to work well. The minimum resistance seems to be around 110 ohms. I haven't wired it up for a signal yet, just breadboarded the test circuit. So there'll definitely be some attenuation but it might be acceptable. Or you could just put an op amp after it.

Interesting.  I was thinking about using optocouplers for this since I have some extra 6N137's and 138's around, but everything I saw on the datasheets made me think it wouldn't work (although I can't remember specifically why now), so I've just been using the standard homemade vactrols (red LED and a photoresistor pointing at each other inside some shrink tube).

Works well but they're SLOW compared to active designs (or a real lowpass gate) and it's easy to kill the LED if you send it too much voltage.

I haven't tried it but if you feed audio scaled and offset to a 0v to +5v range into the LED the whole thing should react slowly enough to be a kind of crude envelope follower.

Pretty interested to hear how the ICs work out for this.

Damn. So I picked up a few H11F1 optocouplers, because those were available, thinking you’d just apply some voltage to them and be presented with a nice, easy to understand resistance. Turns out it doesn’t work that way.

Why does this always happen? Sigh ...

Yeah I think scaling and offsetting are the main reason these simple-seeming utilities have such complex schematics. 

IC vactrols ae designed to work at very high speeds with low voltages for isolating digital signals so it makes sense.

The old style vactrol method works fine for what it is. After work I'll find the schematic I jotted down for the way I was making them (it's pretty simple, one resistor, one DIY vactrol and one or two capacitors, but it's a little different from the instructions I've seen online) and post it.

  On 7/22/2020 at 4:21 PM, sweepstakes said:

Yeah I think scaling and offsetting are the main reason these simple-seeming utilities have such complex schematics. 

Yeah ... math ... barf

Jesus could I get a BOM order right the first time just ONCE in my life?

I love those little SMT LL4148s. They're so cute that I don't even mind how they roll around all over my workspace.