Kequencer
I had an idea the other day and I couldn’t decide if it was good or not so I just built it to find out.
Eight oscillators, an on-button and a pitch knob for each. First you adjust the pitch of each oscillator so they’re vaguely in tune with each other. Then you flick on the sequencer. Then you play polyphonic chiptunes.
So here’s what’s under the hood.
The block on the bottom left generates the clock signal that sets the tempo. C1 & R6 set the clock rate (R1 limits the maximum frequency so you can’t burn out the chip). With that clock signal being fed into the 4017, outputs Q0 to Q7 momentarily go high one after another.
The subcircuit denoted by the circle outline is repeated 8 times. It includes the indicator LED, mode switch S1, pushbutton S2, and oscillator for each of the 8 steps. The oscillator is only on so long as pin 1 is high. This high pulse can come either from the 4017 outputs, or from the pushbutton.
The outputs of all 8 oscillators are tied together via 100K resistors (R5), which is a very lofi way of keeping them buffered from each other. From there the output module is up to you. The simplest thing to do is have R7 set to about 1k – this will drive headphones directly but I can’t quite guarantee that’s a good idea. I used my rudimentary knowledge of opamps to make it more closely resemble a line-level output. In my box I also included a little amplifier module I had lying around so it makes good loud noise on its own.
As always, this circuit is pretty basic, but depends on hundreds of little assumptions – so if you have any questions feel free to ask and I’ll try to point you in the right direction.
Update
Here’s a more complete schematic and board layout. Now there’s no excuse not to build your own!
Update:
Kequencer 2.0, now even tastier
56 Comments
Very cool. And I love that it’s so simple that as you say it’s easier to just build it and see than to figure out whether it’ll sound good or not.
[...] excellent when a simple concept results in something inspiring and fun. [Rich Decibel]‘s Kequencer is a good example, starting off as many projects do: “I had an idea the other day and I [...]
Wow. That is just awesome. I like that such a seemingly simple idea can come together to make something novel.. That is the essence of a great design. It sounds wicked, too.
Quite the bendable apparatus!-(I know, to ‘bend’ assumes some kind of existing circuit being used for other than it was intended)- But what I’m interested in is- is that the bottom of a bread pan? I like it, and would really be pleased if you could please let me (all of us)know what you used for the fascia panel!
The LED in your schematic is upside down. And I dont think it will do the 4017N good, if a “step channel” is “off” and you push S2 when S1 is “on”. Current flows thru S2, S1 and right into the 4017. The internal lowside transistors of its output drivers will suffer doing so.
Looks and sounds amazing. I am just getting into the world of diy synths, with only an Atari Punk Console under my belt. Any future plans of posting a parts list for resistor and capacitor values you used?
The panel is a tray I got from a junk shop. Very awkward working with non-square objects but I’m happy with the finished product.
Good spotting MF, but I think I’ll leave it like this to see if it dies, just out of interest.If anyone wants to copy this project you might want to throw in some diodes to prevent this problem.
As for parts values, it’s a good idea to play around to find good combinations. R1 and R2 can be anything <5k, I used 50k log pots for R3 and R6, C2 I think is 4u7 and C1 is maybe 47u. I used 100k for R5. C3 is for decoupling so it’s not fussy, anything above 2u2 should be fine.
[...] excellent when a simple concept results in something inspiring and fun. [Rich Decibel]‘s Kequencer is a good example, starting off as many projects do: “I had an idea the other day and I [...]
Hi there!
What’s your supply voltage?
I’m thinking of rebuilding your circuit
Greetings,
Jens
This runs from a 9V battery. CMOS is happy between 3 and 15V though, so feel free to experiment. If you’re copying this maybe put a diode on each pin of the 4017 (Q0 to Q7) as protection.
admin: pls can you tell us more about the protective diode? I saw lots of circuits with 4017 and lots of diodes but i am happily using it even without those diodes… What can happend? Is there some possible misuse which can lead to destroying the chip? what are the cases when the diodes are really needed? thx.
BTW i am almost sure that you don’t need multiple oscillators when there is only one playing at time… I can suggest you to use only one oscillator driven by transistor (driven by sequencer) and use the other oscillators to make sound more interesting. if you google bit, you will found that there are quite cool simple circuits with eg. 4093 that are made from couple of NANDs one modulating the other that will enable you to add more juice to the sound (and select the flavour of juice by few more pots
The diode is to prevent VDD going back into the 4017 when the pushbutton is depressed. I haven’t used them in this unit and it is working, but it will probably die pretty quickly.
I used 8 oscillators to make it polyphonic. The chips only cost $1.50 each so it’s no big expense. For more flavour-juice check out my other stuff.
That’s a wonderful example of how easy it is to achieve polyphon-icity.
And a very pretty build, too.
I think resistors (~1k) in the lines from the 4017 will work as well as diodes for solving the double-switch problem…
I don’t know if a 4093 is necessary, since I’ve seen similar oscillator circuits with non-schmitt-triggered gates like a 4011 (cf Lancaster: CMOS Cookbook).
Did you do a PCB?
No PCB, just stuffed 8 PCB-mount pots into some perfboard and freestyled it from there. There’s really not that many components, I figured it was just as much hassle as getting a PCB done.
Thanks for your answer
The protective diode sounds reasonable, yup
Uuhm… what’s R4
?
THX for info. I think i will use the LED directly without resistor even as the protective diode to simplify the circuit.
Some LEDs are able to stand much higher current than one could expect, so i think it’s not a problem when you will not use CMOS on >=9V (actually i didn’t burned my (various) LEDs connected directly between 4017 and ground even when running on 12V) and i don’t expect any high current to be flowing from 4017…
sorry i wanted to say =9V
this is how terrible accidents can happen in high-voltage applications or chemistry
If the 4017 outputs 9V minus 0.7V for the protective diode I should use a ~330 Ohm resistor for R4, right?
That’s about right jensma, though it depends on your LED, as Harvie points out.
i am almost sure that you don’t need multiple oscillators when there is only one playing at time
…except he is often triggering >1 oscillator at once using the pushbuttons out of “sequence”.
Thanks for updating the circuits!
Hey, the leds are missing in your new design
Yeah that’s just a board layout, the leds and switches are off-board so they’re not drawn in.
I’m gathering the components right now. Potentiometers from UK, ICs from germany, knobs from the US. I keep the price low
I think I’ll make the case from scrap wood.
Excellent! If I were building this again I’d add the WSG filter, it’s the best way to add colour to the sound.
Refering to my expanded schematic: replace R5, R11, R12, etc with 1M, then connect the output to the filter from this diagram
Good luck!
That filter looks weird
Do you have any sound footage of it in action?
Not of that specific filter but it’s a pretty standard resonant LP. I’ve got a video of a different LP filter but it’s nowhere near as good as the WSG.
I’m pretty new to electronic music.. the only sound-thingy I did was an atari punk console
LP filters are used to take that harsh sounding square wave from your atari (or kequencer) and smooth it out to be more mellow like a sine wave.
If you want to start experimenting I’d recommend this circuit. None of the values listed are particularly critical, you will get interesting effects from all kinds of parts, so it is a good place to start. Once you are more familiar with filters then I’d definitely recommend going on to the WSG one linked above. It is by far the best filter I’ve heard for such a simple circuit.
I think I’m going for this circuit:
http://www.beavisaudio.com/bboard/projects/bbp_567Mod_Rev_1_1.pdf
Did you made any experience with a circuit like this?
Yeah I’ve made that one before, it makes a lot of fun noises. That Beavis Audio site is a goldmine
Weird…. I put together that 567-thingy twice, but it won’t spit out any noise
Good news!
I started to putt he sequenzer together today. Unfortunatly, a 50K pot wasn’t enough for R6 so I used a 470K. I’ll keep you informed about my progress
Cheers,
Jens
I’m new to this kind of thing, I’ve done a bit of circuit bending before but thats about it. I want to build one of these but I’m finding it hard working out the schematics.
Could you maybe post some images of your kequencer internals to give me a better idea of what I’m doing?
Thanks
Hi Adam. I’ll try to get some gut shots when I’m back from holiday.
As for the schematics, I left them a little sketchy on purpose. I intend them to explain the functional layout without going into specifics for exactly what wire connects at which point. This probably sounds a bit backwards but it’s intentional: I want people to _learn_ from what I’ve made, not just _copy_ it directly.
Functionally:
Each 4093 gate is wired to a capacitor and potentiometer to set up a variable-frequency oscillator. Their outputs are all wired together at one point. The pitch oscillators need a V+ signal to switch them on. This comes either from the pushbutton, or from the 4017, which is continuously outputting a series of V+ pulses on each of its 8 outputs.
If you want to build this, get a breadboard and play around with the 4093′s, see how they work. Then do the same with a 4017. Then come back to the schematic and it should make perfect sense.
Hope this helps,
Rich
Although it’s gonna be more work for me your right about learning and not copying. I’m sure I’ll be much more satisfied when it’s complete.
I’ve got some 4017 and 4093s on there way to me now, I’ve been researching about them and Its all starting to make alot more sense now. would still love to see those pics if you ever have time though
Given that the 4093s have 4 gates and this only uses 1 isn’t it theoretically possible to use them to run 4 sequencers simultaneously?
Thanks for the help,
Have a good holiday
Awesome! I am building one in a cookie tin. Unfortunately, it makes ugly sounds when I push the buttons, due to the thin metal lid. Perhaps I can put something in the middle to keep it from doing that.
OP-AMPS: I bought a LM358 to amplify to speaker level, but I’m not sure how to set up the circuit when it’s running at 9 volts – anyone tried this? The datasheet has a non-inverting AC amp circuit, but that’s when the op-amp is being run at +5V/0V. (Cool that the 358 can do that!) I’m not sure which resistors do what, beyond the two that set the gain, so…
@Adam: at first I thought you meant for the sound oscillators, but then I realised you meant the tempo clock. So, yeah, you could run 4 8-step sequencers, or one 32-step sequencer. I would love that, but those pots are rather expensive (around these parts, anyway).
What I also think would be useful is to add an external clock jack. Thus, this could be modular. Granted, it wouldn’t be that difficult to just adjust them to play in sync, but modules would be neat.
Just another comment, @jensma:
What were you using for R1, and are you running your kequencer with a 9V?
I calculated that, for a range of 0.5Hz to 5 Hz, I would need a range of resistances from 50K down to 5K. What is your formula for freq?
From the NAND gate datasheet, using values for 9V supply and 25 Celsius,
f = 1/(0.863*R*C)
and I am using a 47 uF cap.
I haven’t built that part yet, so I was wondering if I made a mistake…
Ha, I started building pretty much exactly this device last year but I messed something up and shelved it late one night.
It’s still on the bench under a pile of matter where I abandoned it but after seeing yours working I’ll have to dig it out now.
Nice build!
@dewert:
Just 10 Ohm, if I remeber correctly. Mines not finished yet
I’m using a 9V battery.
Ah, I’m going to use this as amp:
http://bertrik.sikken.nl/bat/pix/amp386_2.gif
It’s operational at 9V and very easy to build.
Ok… I’ve built it, but it doesn’t work! Can someone who is more knowledgeable than me help me out? My decade counter seems to count erratically – the led’s flash on and off with no apparent logic.
I was thinking it might be due to a bad clock signal. Since I don’t have an oscope, I put in a piezoelectric buzzer to check it (tempo oscillator output to ground). And voila! The led’s are now sequencing nicely. Obviously not right, since (a) it’s supposed to work without it and (b) I want a sequencer, not a metronome.
Any thoughts?
Hmmm it’s hard to tell from your description dewert because these chips malfunction in all kinds of weird ways. Obviously check all your connections first and foremost, especially the reset and enable (4017 pins 15 and 13). Sometimes if you get lost with CMOS it can help to throw a few pulldown resistors at the circuit – e.g. try a 100k resistor from 4017 pin 14 to ground.
Good luck!
Hell yeah, I finished it.
pics or it didn’t happen!
Here is the ugly clone of the kequencer =D
http://www.jensma.de/upload/files/IMG_20111003_202531.jpg
http://www.jensma.de/muell/Untitled6.mp3
In these days of austerity in addition to relative panic about taking on debt, many people balk against the idea of utilizing a credit card in order to make acquisition of merchandise or perhaps pay for any occasion, preferring, instead to rely on a tried as well as trusted approach to making transaction – hard cash. However, if you possess the cash available to make the purchase completely, then, paradoxically, that’s the best time to be able to use the card for several good reasons.
i want design tempo and pitch for experimenter circuit in schematic
Just an idea… Separate the 4017′s outputs from the 4093′s inputs, and use… patch cords! To tie them together! Each sequence output could trigger several oscillators at once, and each oscillator could be triggered by several outputs. So it could play fully polyphonic tubes!
All you’d need to do is separate the chips as I mention. Then put a 1-pin socket on each output and input. The patch cords would each need a diode included, and so would only work plugged in one way round. This would stop trigger signals from one note travelling back up the wire and activating others that are meant to be connected together but to other triggers.
This small mod would give you a pretty solidly basic, hard as it comes, hardware sequencer! With all 8 notes playable simultaneously if you like! At the moment the only polyphony available seems to be by manually pressing the buttons, this would be all automated by just the addition of some wires with diodes.
A simple mod would be either to add another octave, 8 more notes, or to extend the steps to 20, or more, using extra 4017 chips chained to the first.
The patchcord method of “programming” really makes the circuit’s operation clear. And simple enough even to, say, let schoolchildren make them as a GCSE / high-school project.
Also, to answer WestW’s question (of a few years ago, sorry!), I’d guess using a non-Schmitt gate would give a different sound. You can get sine-ish waves using CMOS gates as oscillators in linear-ish, “analogue” mode. I’d guess the Schmitt gates sound more square wavey. Certainly would be something interesting to try, especially if the parts are pin-compatible, you could just switch one chip out for another.
Oh hellls yeah Sam, great suggestion. I gotta make one of those!
I’m anticipating it with excitement!
Actually regarding WestW’s question, I’ve seen NOT gates used in the past as simple analogue audio amplifiers. I suppose getting the input bias right is the trick. You can probably find it on the web. It’s not hi-fi, but then that’s not what we’re after, right? Maybe that itself would be an interesting box, a non-analogue non-digital amp!