Posted: Tue Feb 24, 2015 4:07 pm Post subject:
Logic Noise CMOS synth series at Hackaday.com Subject description: Inspired a great deal by y'all!
Hey folks,
I'm currently writing up a weekly column at Hackaday.com on noise-making with CMOS chips.
I've cribbed ideas from everywhere, naturally, including here. So I thought I'd first of all say thanks, and second, head on over and have a look / listen.
So far, we've built up a 40106 square osc and enriched it a bit by hard-syncing two oscs together. Then, played around with the 4040 binary counter to make octaves. Finally, hooked the counter up to a 4051 switch to make a pitch / timbre (through the sync osc pitch) sequencer.
Next week, I'll dig into some of the more analog-y options, using a 4069UB to buffer up the triangle wave on the input of the 40106, and then playing around with overdrive options and simple filtering.
And then after that? AR-VCAs? Voltage controlled sawtooth? More counters? 4046 tricks? Beats me. Any thoughts?
The main constraint is that it's ~30 minutes worth of build-time for the projects per stage, that they cumulate, and that you get something kinda cool out.
I've been liking the one-chip-per-week pace, but it's not set in stone.
If you've got a favorite, high output/effort ratio circuit, let me know in the comments at Hackaday or the forum here.
And if you've got any other feedback for the column, positive or negative, let me know! I'm always stoked to hear back, and y'all are my (ideal) target audience. Last edited by hexagon5un on Thu Feb 26, 2015 3:31 pm; edited 1 time in total
Maybe the diode vca? I think if you forum search that you'll get results. There is also the transistor vca that Synaesthesia uses, which is basically the same principle. Really good "bang for your buck"
Hello hexagon5un, saw your column as well. Great work, very well written and illustrated!
There are plenty of interesting circuits around the 4015 shift register, so that could be an interesting IC to introduce as well. For example, search for WAVESHAPER and replace the 4006 by a 4015. Other ideas for simple circuits that come to my mind are:
o use all inverters from a 40106 and introduce power starvation (search for STARVIN MARVIN from PHOBoS)
o introduce the 4093 NAND or 4030 XOR gates and build something that combines different frequency divisions from a 4040 (search for MELOGITRON)
o use a 4030 XOR or the XOR gate from a 4046 for pseudo ring-modulation of two signals
o because the 4093 NAND has Schmitt-Trigger inputs, it can be used to build oscillators as well, these can be gated using one of the inputs
o the simple triangle oscillator is a nice building block, you can use a 4069 instead of the 4049 inverter
o the 4017/4051 melody generator is almost a must, variants with more tones and micro-tonal or chromatic scales can be found here as well
o introduce the 4046 VCO (ignore the PLL for now) and drive it with two mixed sawtooth or triangle waves for great sounds (search for SPACE4046 in this forum)
o the 4015 dual shift register or the 4093 NAND can be used to build a stepped-tone generator similar to the ATARI Punk Console (search for APC in this forum)
o with the 4051 and 4015 (and an optional 4040) plus oscillators you can build circuits that play fixed melodies (search for CHIPTUNE in this forum)
Joined: Jan 14, 2010 Posts: 6067 Location: Moon Base
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Posted: Wed Feb 25, 2015 2:29 pm Post subject:
4017/4051 melody generator and CD4046 VCO was the first things I thought of aswell.
Another nice thing would be a Linear Feedback Shift Register for some random bits
or at high speeds chipnoise (you know the explosion sounds from old atari games ) _________________ "My perf, it's full of holes!" SoundCloudBandCampMixCloudTwitchYouTube The Golden Shrimp Guild
Joined: Feb 27, 2014 Posts: 26 Location: Redondo Beach
Posted: Mon Mar 02, 2015 4:26 pm Post subject:
Your series is very cool and you always mention using LDRs; I would suggest delving further into the fun to be had making more precise modulations from LED/ LDR combos. LED arrays driven by 4040s/4060s, 4017s and the like can produce fantastic modulations. LEDs triggered by MIDI notes will allow you to modulate the oscillator from your DAW.
Your series is very cool and you always mention using LDRs; I would suggest delving further into the fun to be had making more precise modulations from LED/ LDR combos. LED arrays driven by 4040s/4060s, 4017s and the like can produce fantastic modulations. LEDs triggered by MIDI notes will allow you to modulate the oscillator from your DAW.
Hah! I was just thinking of whether or not to run an in-depth LDR session just yesterday.
I've played around a bit with trying to characterize LEDs hotglued onto LDRs and wrapped in black electrical tape -- essentially a DIY vactrol. But with the grab-bag of LDRs that I got from some surplus shop like a decade ago, they're all different. And seem to respond to different LEDs differently too.
In short, I wanted to get something precise out of this, and basically failed. (Not that I failed. I ended up just hard-coding a table of experimentally derived PWM duty cycles for the specific LED/LDR pair into the code for the microcontroller that I was using. Good for a one-off, but it doesn't scale.)
But yeah, I'm trying to think of ways to easily work voltage-control into the series, and I wanted to go the LED-LDR route too. Although mostly because I've never messed around with FETs as resistors, and OTAs are waaaaay to complicated and fragile.
Joined: Feb 27, 2014 Posts: 26 Location: Redondo Beach
Posted: Tue Mar 03, 2015 1:59 pm Post subject:
Here's a simple relay board I put together a couple of years ago for a percussion installation, but it also makes a great interface for lunettas and the like; each LED corresponds to a MIDI note and when the LDR on the right is hooked up to the oscillator, pitch control and other modulations are available from a MIDI keyboard/ sequencer. Preferably in a dark room.
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Seriously, that's pretty cool. You were controlling pitch? I can't imagine that this thing would be tuned. (Not that I'm asking for it to be tuned.)
But really neat idea to use combos of LEDs in a row like that, so the close ones affect the LDR more than the far ones. Was 20 overkill? How much light did the last LED add?
I've only ever done multi-LEDs where I put them all just about the same distance clustered around the LDR. Like petals on a flower, basically. It was good for polyrhythms, but there wasn't any real attempt at finesse.
And man, I'm sad. I just read up that CdS photocells like these are no longer being produced (or legally put into products?) in Europe. Will we have to figure out an alternative?
And has anyone played around with photodiodes or phototransistors in this type of application?
I just read up that CdS photocells like these are no longer being produced (or legally put into products?) in Europe. Will we have to figure out an alternative?
AFAIK, they can't be imported and products using them can't be imported into Europe. There are other types of photoresistors but I've only ever seen them for infrared spectrum so I don't know if there is a Cd-free alternative. There may be little incentive for one to be brought into production also. Fun as they are for us DIY types, commercial applications might be limited.
Joined: Feb 27, 2014 Posts: 26 Location: Redondo Beach
Posted: Tue Mar 03, 2015 7:45 pm Post subject:
There are 24 LEDs simply because the MIDI/ PIC board that drove it was 2 octaves. It does give pitch tracking in that the furthest light will give the lowest note...the main benefit is the fairly accurate repeatability of patterns. Makes a pretty good LFO too when programmed with 2-octave arpeggiations.
Here is a suggestion for a simple circuit with a 4015. It is basically a scaled-down version of the Opus4015 circuit from another post in this forum. You can also find the RandomChiptune circuit there using a 4051.
The amplifier in the schematic is for a small module that I built for a friend. It might be useful for others experimenting with Lunetta circuits as well. The circuit is a simple transistor amplifier as you can find it on the Talking Electronics web site. The module is designed to plug vertically into a breadboard and includes a small 0.3W speaker. The left and right connectors go to the upper and lower power lines on the breadboard, the middle connector is for the input. There is even a small trimmer to adjust the volume. The quality is pretty good, definitely good enough for Lunettas.
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Up next is filters & simple twin-t drums, also using the 4069UB. Then after that we'll need a VCA and envelope or some trigger circuits.
Then, we're ready to start cobbling it all together. Counters + switches + EG + Osc + Filters = good times. Which also sounds like a good time to start throwing shift registers into the mix.
a littel sugestion: especially at the last video i wud be verry nice to see your scope in the video.
Heya Matze,
that's on my list of things to do! Hopefully I'll be able to pull that off next week. My scope has a VGA out, but I can't figure out how to record it directly. I think I'll have to point a camera at the screen, which means pulling the blinds and removing things that reflect off of it, etc.
But totally. A scope overlay would be great, especially for next week, when I do ADSRs. (OK, maybe just an AD/AR.)
And a long, long overdue thanks for all of your stuff here, including but not limited to the great Lunetta overview doc. Can't say how many people I've passed that link off to. (I'll have to do a sources post sometime, but the compilation alone will take a week...)
The chip of the week is the 4017, and basically covering some simple interfacing tricks.
These include getting it to work with a 40106 oscillator, the twin-t drum circuit, and a 2-diode vca. With a side-helping of diode-logic ORs thrown in for good measure.
Next time we'll take on the 4015 shift register.
I'm thinking of just straight-out copying one of your nice circuits, Synaesthesia, but we'll see how much space I have. If not next time, then uber-next.
The topic is the 4015 shift register. Along the way, we build up a Slacker/voks' Melody Generator, and I turn them all into a simple / random tap looper.
It was a really fun session to make. I love shift-register sequencers. Hope you enjoy!
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