super simple 40106 VCO with expo or linear control

synthmonger

Be sure to read the notes! ;D

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synthmonger · Posted: Mon Sep 08, 2008 11:55 pm Post subject:

Err there's an error in the schematic. The linear cv should be +9 volt not +12. It'll work on 12 but you'll have to change some values I'm sure.

slabman · Joined: Sep 01, 2005 Posts: 102 Location: UK

Thanks for sharing this. Looks like a great way to munge together a Weird Sound Generator with a Soundlab.

synthmonger · Posted: Tue Sep 09, 2008 2:53 pm Post subject:

bunch more uses of the 40106 on the way.

Rykhaard · Joined: Sep 02, 2007 Posts: 1290 Location: Canada

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

i bread boarded this up the other day on 5v. and got nothing i think im going to try and knock down the 1m's to 100k and see what happens? excited to get a tri out of a 40106 though!!

synthmonger · Posted: Sun Sep 14, 2008 11:50 pm Post subject:

I was using 9V and 12V. Not sure if 5V will work.

The linear portion really isn't linear and only have a range of a couple volts. Make sure you're connections and transistors are facing the right way, I'm 100% certain this works.

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

got it going i had a 2n reversed. very cool thanks!!

synthmonger · Posted: Sat Oct 11, 2008 11:16 am Post subject:

Remove C1 and add trim pot on the negative end of the manual voltage control to get a high frequency vco.

Pehr · Posted: Sun Oct 19, 2008 11:30 am Post subject:

is there any chance of getting exponential control with single supply psu?

synthmonger · Posted: Tue Oct 21, 2008 2:41 am Post subject:

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

Ok so I looking at this cuircuit again the other day. On a 5v supply I changed r1 to 10m, and c1 needs to be atleast .22uf. Now I was using a .22uf Mylar cause it was the biggest I had on hand. This gave me a frequency of about 1.6k hz. I wanted more freq I tried a 1uf electro and the top end of the ramp rounds out? Is this because the electro cap? I'm going to be making a local run to a shop that has polystyrene caps in higher numbers. Maybe this is what I need...

synthmonger · Posted: Mon Mar 16, 2009 2:02 pm Post subject:

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

I'm building my lunetta almost as like a 5v CMOS learning lab. I should prototyping cause nothing has made it off the breadboard or off cardboard yet. I may re concider 12v? Idk....

Rykhaard · Joined: Sep 02, 2007 Posts: 1290 Location: Canada

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

So ryk you are using 9v? Synthmonger is using 12v. I honestly thought you where using 12v also. I keep hearing using 12v will make of easier to intergreat to my modular. But what iwas thinking was that. I will have any easier time seeing what the CMOS is doing on 5v?

scriptstyle · Joined: Jan 22, 2008 Posts: 250 Location: nj

Something occured to me just now while reading the thread you just started about using a 4007's gates. This is my secound time working with this schematic and the last time I remember geting a good range of osc with a cap around 1n, but like I mentioned earlier ihad no such luck this time. Just high freq osc. Then I remembered I did have a pullup resistor before c1 the first time around. Should that make the difference?

Rykhaard · Joined: Sep 02, 2007 Posts: 1290 Location: Canada

ashaxx · Joined: Jun 15, 2009 Posts: 7 Location: uk

sorry for such an amatuer question here but is the Circled A the audio out?

jean-louise · Posted: Fri Sep 04, 2009 8:41 am Post subject: Re: vco

slacker · Posted: Fri Sep 04, 2009 10:07 am Post subject:

Yeah that's right it's just the point where you connect either of the converters. The audio out is the "Falling ramp out".
You could technically use point A as an audio out providing that what ever you connected it to had a high input impedance, otherwise it would load the input of the inverter and stop it oscillating. That's basically what Q3 is already doing in the circuit.

Psyingo · Joined: Jun 11, 2009 Posts: 248 Location: Canada

I boarded one of these and it's really great. thanks for posting a schematic. I enjoy your circuits, synthmonger.

synthmonger · Posted: Mon Sep 14, 2009 4:10 pm Post subject:

By the way, use an op-amp buffer on the 'sawtooth' output. 4069 inverter gates would probably do the trick too. This gives it better if not perfect symmetry.

synthmonger · Posted: Mon Sep 14, 2009 7:14 pm Post subject:

Oh and if ya plan to build multiple VCOs out of one chip I'd limit it to a max of 4 so they won't bleedthrough/modulate each other. Keep the middle inverters grounded.

I like to stick with two VCOs in a single chip. I use three inverters wired in series with the first two for the sync input and the last one as the vco core.

Oh and I found a neat way of getting 1-100% PWM using 3 gates. It sounds pretty different than you're typical op-amp pwm configuration.

...I should spend some time posting schematics for these...

Psyingo · Joined: Jun 11, 2009 Posts: 248 Location: Canada

yes please, moar schematics!