Friday, September 28, 2018

Tape Deck Mult Panel--An Easy One (Two)

Nothing like finished panels....

I guess I like the Tascam SS-R220 stereo solid state recorder....I own three of these....
What is good about these?

  • Good bang for the buck
  • Decent A/D D/A without paying a fortune
  • Digital IO so you can use better D/A if you want (I use a UA 2192 and one of these for mastering--always liked the way the 2192 AD-DA sounded).
  • The SS-R200 RCA inputs accepts synth 5V P/P signals without a lot of fuss
  • Good, easy to use front panel UI
  • Good manual
  • Works on SD cards, which are cheaper (and taste better) than a Big Mac
  • Remote control with a long cord (hey!)

In other words, someone at Tascam did good work on this one.

So what does this have to do with DIY?  I want to do sound on sound, 2 of these in one rack, so I figure I'd build a couple of quick mult-panels to accommodate, with some normals etc.

After sleeping on it, bingo, I know how I want to do this.

Hand drawn wiring setup (rear view) looks like this:

I use 3.5mm "normalled" TS jacks for my DIY work--I had to choose something, and always thought on the ARP2600 this was a good combination of size, convenience, and ease of using normals.

I already had about 6 unpopulated alubase panels I got from PCBWAY.

From here building 2 of these was easy work.  After mounting jacks and soldering up the mults and normals, I cut the one end off a couple of junk RCA stereo cables I had and used the cable and remaining males.

Here it is in my Fracrak:

Still need to label the panel, using Lazertran, but I am finished with the artwork already:

One of those things that's fun and easy.  

OK off to put some guitar parts through a Balanced modulator.  I'll have sound samples soon.  Really!

Sunday, September 23, 2018

Getting started with AudioDIY and the Atmel ATTINY85: What to do with these tiny things?

UPDATE!: I have written two additional posts (so far) about ATTINY:

Pros and cons and debugging here.
Arduino Interrupts using ATTINY85 here.

OK back to the original post:

Hello Again! I can't help but be seduced by an Arduino that, from about a foot away, looks like an op amp. And costs only a bit more!!!

I'm talking about the ATTINY, which in its "85" form looks like this:

Can we really pack an Arduino punch into an 8 PIN chip?

Time to find out!

I bought a few of the ATTINY85's ($2-3 for DIP, good for prototyping; under a dollar US for surface mount) and a Sparkfun programmer for about $15 from Amazon:
From my reading, programming ATTINY using the Sparkfun is pretty straightforward--I figured I'd have the LED blink app up and running in 10 minutes?

But it didn't work!  10 minutes became a couple of hours....


I have 2 computers I use for Arduino programming on my bench and the Sparkfun programmer didn't work on either: an older MacBookPro running OS-X Mountain Lion and a Lenovo T430 running CentOS 7.  I have used both many times for programming Nanos such as the one used for the SynthDMV.

After following the Sparkfun instructions (which are very clearly written--good work Sparkfun) several times, no go; it's like the system couldn't find the ATTINY85 chip I had put into the programmer.

Driver issues?

Many documents on the web say for Linux and Mac you don't need drivers for this Sparkfun Programmer--only for Windows and thankfully I don't do Windows in my electronics lab....too much Windows at work, don't need that here as well!

But still it felt like a driver issue.

Lots of head scratching....odd that I saw this "hide the ATTINY" issue for both laptops (different OS's right?  different hardware)?

To make a long story short, I found other poor sorry fellow dumb SOB's who had the same problem, and one of them suggested "try a different USB cable".  Well, I wasn't using a USB cable at all; I was just plugging the programmer into an open USB port of either laptop.  Seemed at best like a long shot but after 2 hours of messing around with this I was ready to try anything.

I dug around in my USB cable crapola box and found a M/F USB 2.0 extender--a standard M/M USB cable wouldn't work--I plugged the Male into the Mac, the Sparkfun programmer into the female side, and of course after that the programmer worked!

Now that makes no sense at all....i could see the programmer being unhappy with the USB port on one laptop, but not two, and running different OS's at that--and it didn't work on any USB port anywhere, but with the USB extender cable it worked everywhere.  Makes no sense!!! 

I posted this on an Arduino Forum and got zero responses, so maybe of the 7.7 billion people on the planet I'm the only one to have ever have had this problem?  Whatever.

UPDATE!! FIGURED It OUT! It had nothing to do with cabling, drivers, or anything else. both the mac and linux machines are linux based and both weren't giving the programmer permission to program. I still don't know why the system worked after I changed out the cable, I must have done something else (run arduino IDE as root?) total mystery until I found this. Here is how to fix this issue:

  • From your linux box, open terminal 

  • issue the command 


  • note in the list which one is TINYUSBISP: for me it is this: 

Bus 003 Device 030: ID 1781:0c9f Multiple Vendors USBtiny

  • now issue this sudo command where the last 2 numbers match bus and device numbers spat out by the lsusb program. 

[clamm@localhost ~]$ sudo chmod 666 /dev/bus/usb/003/030


Onward!! Anyway: now that the BLINK proof of concept is working--a few things to think about:

  • There is no "official" I2C library for the ATTINY.  I see folks using this "BroHogan" i2c library; I have yet to test it.  So my favorite I2C goodies like the MCP4725 D/A are not supported using the more familiar wire.h library, but that's probably OK.
  • SPI is the same deal--but you can apparently use this guy's software to do SPI with this chip.
  • There is a LED on the programmer--D0--that does help a bit I guess.
  • There is no built in serial I/O in this system, which makes debugging harder.
  • You have to supply your own 5V power supply--to power the chip as well as any peripherals--there is no 5V regulator on board, as there is on the nano.
  • Tinkercad Circuits, which I use all the time to bang out virtual Arduino code to then use in the real world, supports ATTINY. And from messing around with it so far: at least some of the slightly more arcane features, like Pin Change Interrupts, appear to be supported.  yeh!!!
  • The Programmer you see above has breakouts for the pins on the ATTINY--so you aren't schlepping the chip in and out all the time--very useful.

OK time to put this on the bench:

Yes, blink works, analog in works, basic interrupts work, and so on.

After an afternoon of messing around, two designs came to mind that might be good candidates for projects based on this chip:

CMOS 4051 based CV selector based on incoming control voltage:

The CV is read by an analog pin (need to condition the CV to be 0V < x <5V, but that's not too hard) and then used to switch between CV fed to 4 or 5 of the 4051's inputs.  Any audio would have to exist between 0 < x <5V as well, but if you can massage the audio to that range, that should work as well.  That's all simple op amp stuff right?

Update!  I have this 4051 switcher working in a simulator, read about that here--the 4051 business is at the very end of the post.

Or, a low parts count (I think) trapazoid generator:

Hope I am not using too many IO pins here!

Overall though I keep going back to this nagging thought--why not just pay an extra $4 or whatever and use a nano clone? You get more pins, more options, serial for debug, etc. Of course the Nano is bigger, but not too big for projects that involve 1u Fracraks which is the smallest thing for which I'd probably use Arduino.

So I am left wondering what if anything AudioDIWHY I will use ATTINY for? Guess time will tell....

BTW I think these guys are burning audio stuff onto ATTINYs and selling them as finished audio DIY chips.  So the tenement version of a VLSI chip making operation. Just a guess? Makes sense--and if that's what they are doing: clever.

Regardless it's cool that fellow hackers have made an Arduino IDE-ready chip that's this small.

OK that's it.....Until next always, don't breathe the fumes.

Wednesday, September 12, 2018

Mad Bees! Avalanche Ramp Oscillator--Smells like Insect Spirit

Greets again fellow synth nerds:

I broke my own rule of DIY and perfboarded a new design. The rule: I figure it's quicker these days for me to use Eagle to craft a PCB I want to mess with, kludge in any parts, and see if I can get it to work. If I can great, if not, toss it and start over....but not this time....

The back story?

I was up late watching my usual youtube electronics vids to help me fall asleep (Carlson's lab is a favorite for that! 2+ hours of a Canadian tech saying "abooot" while restoring a tube amp? This guy is awesome!) and came across this Colin Furze clone DIY audio dude. At least he's a synth player, he doesn't ride around on jet powered bicycles and you gotta love that earring!

Close enough!

OK Sir Thomas Dolby-Colin Furze's kid brother has a super fun series of vids about using a NPN as an "avalanche oscillator".  (BTW I really like his videos! All kinds of great stuff! Mr. Carlson's energy and then some! be young again...Like, subscribe, comment + notify, you know the drill)

I have seen avalanche circuits using zeners but not this.

His design (he probably borrowed it?) was so simple I literally jumped out of bed and bread boarded it. 1AM!  And I had to work the next day. Yow.

Oh yeh, There is a big-butt mistake in his first vid--what you get for "You can skip this ad in 5 seconds".

LookMum shows a pink explosion schematic with the 3904 upside down--being British he was probably using a BC series--yep pins are flipped, but otherwise, once I caught that, it worked.

The next day I perf'd it.  Hours of fun....

here is the schematic I ended up using for my perf-non-masterpiece (?)--a bit more complex than what LookMum shows....and BTW my circuit worked with the 3904 center pin not cut off...but who cares?

As this Sam LookMum says, you need to mess with the LED's to get different sounds, by George! I used 3 LEDs, a flame LED (you know, it flickers, used in fake electronic candles), permanently wired up to the 3904, a small green LED, and another flame LED. A single switch controls the outer 2 LED's.  The green LED, when goosed with the right right frequency, sounds to me like a bee! Bugger off mate! For the other two I labeled them "worker" (audible random burps) and "queen" (nastier bigger/hairier audible random belches and burps).

Another minor detail Sam lookmum doesn't mention: if you perf it up his way, unless you invert the CV, higher voltages lead to lower pitches--but who cares?  I stuck my CV through an op amp inverter (right-side up bee on finished panel) as well as not (upside-down bee). Whatever....

For those playing along at home, here's a youtube of the nearly finished circuit at work....

And--Here a Soundcloud mp3 I did in about two minutes--it's just different bee samples recorded directly to a VCA and out to my DAW, multitracked then mixed together with some reverb.  If I can do this in two minutes, figure what you can do in 5!

The obligatory "circuit on the bench" photos....

Here's another.

Done! I already had a front panel from PCBWAY left over, so this was easy to finish. decal'd it using Lazertran....bolted it into my Fracrak, next to the random gate which is a good CV source for it.

What next? I  have already designed a PCB for this, it would be fun to do 3x or 4x in a dual gang FraCrak panel, sort of what I did with the 40106 design for the Lunetta VCO.  But then I have to get it fab'd then test it, one of these days?

This is a super easy and fun DIY circuit, highly recommended!  Until then don't breathe the Canadians!

ProMicro HID Keyboard Emulator

Quick one this time. The Arduino ProMicro (examples here and here ) is based on an Atmel 16u4 MCU and has HID keyboard emulation ready to go...