A 100% Lunetta vco

synthmonger · Last edited by synthmonger on Tue Mar 10, 2009 10:04 pm; edited 1 time in total

Still working out the kinks but I've replaced the transistors in my 40106 vco with some gates from a 4007 and it works pretty dang well! The distortion isn't as great and the range is about 5hz to well above 20khz. I haven't tested the max frequency but it's definitely inaudible and coming up pretty smooth looking on my scope.

I'm using one of the spare gates to buffer the triangle output so it can interact with things without "flopping" out. I need to amplify it as well since it's only peaking out at about 2v.

I have pulsewidth modualtion, a better sync and hopefully some sort of waveshaping. Ideally skewing and/or sine wave output. All using the extra gates of the 4007.

I plan on making a board for it and will be posting it here. Schematic hopefully later tomorrow...er well today.

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

Looking forward to that then, as I DO have 1 x CD4007. Smile

synthmonger · Posted: Tue Mar 03, 2009 1:54 am Post subject:

Okay so I found out adding a Cap and a resistor at the output of the triangle gate solves it going floppy when applying the output to a voltage input so that saves me a gate.

Now I have one gate left on the 4007. Either I can use it and a spare 40106 gate for an extra pulse width output, or another vco without pulse width modulation...bah maybe I should just make a couple versions.

I also found some gnarly waveform outputs on different parts of the PWM circuit. Squarish-sawish kinda shapes that are skewable via the PWM input. Fun stuff for sure!

Sleepy time now. Work in a few hours and afterwards back to the bench!

synthmonger · Posted: Wed Mar 04, 2009 1:28 am Post subject:

I spent much time knob twiddling today and felt the need to record it.

For now the audio in my recording is from the same 40106 and VCOVR combo in my previous design with the NPN/NPN trannies replaced with gates from a 4007. The audio in the demo is the square then triangle output. The vco is being FM'd by the 2nd oscillators VC "skewable" output, then triangle, square, and pulse output. The 2nd VCO is at times being sync'd by a spare 40106 oscillator. I've revised the sync to reflect a more standard sync sound.

While I'm very satisfied with my new vco I think I'm going to focus on using just 4007s and 4069s. I know it's possible to make a complete standard modular synth using just 4007s and I might end up doing that. Sounds kinda fun, amirite?

droffset · Posted: Wed Mar 04, 2009 1:59 am Post subject:

Sounds awesome, I'd like to make one!

monokinetic · Joined: Aug 01, 2006 Posts: 100 Location: prague

synthmonger:
you are rite Smile

like the mp3, I'm impressed that it's all lunetta.

Hoping you have time to post the schematic soon (although this weekend I'm sworn to Ryk's new oscillator!) Very Happy

David

synthmonger · Posted: Wed Mar 04, 2009 2:08 pm Post subject:

synthmonger · Posted: Tue Mar 10, 2009 10:38 pm Post subject:

Still having trouble working an expo source out of the 4007. I'm making Osamu's Hoshuyama's version of Rene Schmitz's 4069 vco. I'm using Rene's expo source but replacing the transistors with the ones inside the 4007. I can use one of the 4007 gates as a standard NPN current sink to make it an acceptable and fun VCO but I want to get expo for 1v/oct.

Any suggestions? I've included a very early schematic of how I'm using the 4007. I am using decoupling caps and offset resistor for proper tuning, I just didn't include them in the schematic.

Before anyone says anything, the max operating voltage of a 4007 is 18 volts and has continued to work fine at the bi-polar voltage levels.

I originally intended on using a 4049 to produce -7 volts but it didn't provide enough current to power the 4007. I was getting alot of sloppy slewing so I just switched to a MAX1044 which has been working fine now.

4007_current_sink_and_expo_source.bmp

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synthmonger · Posted: Tue Mar 17, 2009 2:51 am Post subject:

Still no luck finding a good expo source out of the 4007. Works great as a current sink but I'm not sure when I can get the 1v/oct worked out.

In the mean time with some tweaking you can use the 4007 sink schematic I posted for a fun 4069 vco. If you want it even simpler then stick a voltage divider onto pin 13 in series with a 50-100k resistor.