Simple CD4046 VCO

wetterberg · Joined: Jun 27, 2008 Posts: 48 Location: denmark

Nice!

madskill42 · Joined: Jun 30, 2011 Posts: 25 Location: czech rep

I've tried this few days ago and finally I can get you some review.

My setup was following: 40106 generating clock for 4017 4 step sequencer, outputs paired via diodes to a VCO input of 4046, 10k pots to control voltage of steps. 10nf on 6-7 pins.

Well, as I tried it, it worked, but somehow there was still a signal output when no voltage was applied to VCO input. It was strange, because I noticed that there's "jump" between each step. So I pulled one connection from step to create "no output step", basically 0v and voila, there was a still output. As I went further with tweaking and trying different caps and resistors, I've managed to pull up resistor at pin 12 and suddenly, that problem was solved.

Is it normal behavior?

nathanxl · Joined: Apr 24, 2012 Posts: 59 Location: Wa

nathanxl · Joined: Apr 24, 2012 Posts: 59 Location: Wa

Here is my attempt at Slackers 4046 VCO mod.
All info on the youtube page.

JingleJoe · Posted: Wed Jul 04, 2012 6:34 am Post subject:

I'd like to take this opportunity to say; that's fucking brilliant Shocked

Would I be correct in assuming the nice "weeep-bumv" sound is from LDR controlled oscillators and LEDs?

nathanxl · Joined: Apr 24, 2012 Posts: 59 Location: Wa

Cheers JJ.
The only Oscillators going to the amp in this vid are the 4x 4046 VCOs on the breadboard there. The "weeep-bumv" modulation is from the slewed 4bit R/2R.

This was a test to see how the VCOs handle the Blue Missile Cluster DAC Im fiddlin with at the end

Im yet to experiment with the LDR/LED Osc' in the mix. Am currently looking at building a VC or gated mixer or a VCA.

Im so happy with this VCO hack of Slackers. Really nice harmonies are possible when the pot is set at 10:30 or 1:30, with just the right amount of slew its almost vocal at times.

Draal · Posted: Wed Jul 04, 2012 12:18 pm Post subject:

Awesome set up Cool

. Yes, every lunetta would be enhanced with a 4046 in it; whether it be pitch tracking as in mine or as you have shown as a vco. A rewarding chip to say the least.

Thanks for the inspiring clips of your work. salut

tjookum · Posted: Sat Jul 07, 2012 2:19 am Post subject:

nice one!

Have you ever seen the work of the man stanley lunetta himself?
http://moosack.net/stang/sculptures.html

nathanxl · Joined: Apr 24, 2012 Posts: 59 Location: Wa

I think subliminally I must have taken his work in at some stage in the past. Similarities are in the interest of having a performance/installation selfplaying sculpture. Thanks. I need more VCOs, specifically VCLFOs to make sequenced loops of one week or more. 4046 VCLFO possible?

Inventor · Posted: Sat Jul 07, 2012 11:44 pm Post subject:

Slacker, I would like to use your VCO circuit in my emSynth product line, with your permission of course. In the event that the circuit sells well I would like to offer you a (very) small royalty for providing the design. If you were to characterize the circuit, providing RC plots and other data then the royalty could (slightly) increase. Just let me know what your thoughts are on this, thanks.

Les

tjookum · Posted: Sun Jul 08, 2012 3:27 am Post subject:

@nathanxl: easy, just use a huge(100-1000uF) cap or a divider like the 4040.

nathanxl · Joined: Apr 24, 2012 Posts: 59 Location: Wa

Here is a handdrawn schematic of my first VCO. Based on Slackers dual 4046/single pot mod.
Excuse the unconventional way of laying it out as it is also the first time I have drawn a schematic...
Some of the circuit design may be a little weird but it works just fine. I have spent 2weeks plugging away at the breadboard, basically trying ANYTHING at all to see what works. It was fun and I think I have made something that is very playable.
It has a gated Hi/Lo cap switching feature using a single 4066. It works great and creates some real interesting rhythm, even better is, without a gate input the 3way cap switch still works. They can be used together aswell and with a slewed CV input all manor of goodness ensues.
I will make a short video of it tomorrow and post up here if there is interest to see it in action.

4046VCO with Gate switching Caps.jpg

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Draal · Posted: Wed Jan 16, 2013 8:09 am Post subject:

I wanted a simple vco for my Mastodon Lunetta and slacker's design fits the bill. I'm sure you all know how much I enjoy using the 4046 so I tend to have a number of these little buggers.

The things I did differently than Slacker (his design works very well BTW, I'm just describing what worked for me).

1. Since this vco is patchable to other things other than just an r/2r, pin 9 needed a pull down resistor to work properly. Without it, I was getting cool noises but was quite erratic in action. Sometimes ya got the weird noises, other times, nothin'. If you touch the pin you could "activate' the vco in a way, so a momentary push button switch that punches the pin to ground could be fun. For me I kept it as a standard, reliable vco by tying that pin to ground with a 50k resistor.

2. Pin 12 broke off my 4046 (hazards of dead bug approach Rolling Eyes

) so that has no resistor on it. It doesn't in the pitch tracker and still functions, so if ya don't have a 4.7M resistor, don't sweat it. However if you want a very specific range of audio freq's, pin 12 becomes very useful.

3. Instead of a 10n capacitor between pins 6 and 7, I used a 100n or 0.1uF cap. Play with this value to tweak your freq. Smile

4. Tied pin 14 to V+. You can of course use this as another input for more fun but I wanted to keep this module as simple as possible.

While experimenting with this layout I had some funny moments of picking up radio stations and being able to modulate them depending on the patch going into the r/2r. Hmmm, mistake or unique option Laughing

!

PHOBoS · Posted: Wed Jan 16, 2013 8:59 am Post subject:

I'm having some fun with the 4046 at the moment myself Very Happy

I really like how clean it sounds in the high frequency range.

I don't have a pulldown on pin 9, but I do have it hooked up to the output of an opamp, with a 500K series pot and 1uF
cap to ground for a glide effect. I guess you would normally need the pulldown resistor when you're not connecting
anything else to it.

From the datasheet I understood that pin 12 can be left floating, what a resistor does is add an offset to the frequency.
(smaller makes it higher) So no real need for a 4M7 resistor.

I''m currently using a 22nF cap between pins 6/7 which gives a nice range of frequencies, all audible. I also have a 500K pot
from pin 11 to GND.

Instead of connecting pin 5 directly to GND I use a pulldown resistor, and by making that pin high the VCO turns off.

I don't want to make it too complex either (ahum,..) but just did a test using it as a tracker with the 4017/4051
melody generator between pins 3/4 like jcintheus did, and that IS fun.

jcintheus · Joined: Oct 16, 2011 Posts: 52 Location: Colorado

Using a 4089 on pins 3&4 is another source of good fun. The result is kind of a "harmonic content shifter".
Or, use any number of 4046's with different divider/capacitor setups,
and the same/similar CV's for "harmonic compositions".
In series or parallel! VCO or Pitch Tracker!
And keep on going!

-minus- · Joined: Oct 26, 2008 Posts: 716 Audio files: 13

-minus- · Joined: Oct 26, 2008 Posts: 716 Audio files: 13

Don't worry Lunettists! I think I've figured it out. Pull up pin 12 4M7R, pull down pin 9 100K (unwritten standard). The thumping was probably me cranking the pot to ultra high frequencies and the voltage on/off on the ladder thumping. Seems to be ok now... "who gives a f*** as long as it makes cool noises" right Wink

? (another unwriiten standard)