electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
More voltage controlled 40106 fun
Post new topic   Reply to topic Moderators: mosc
Page 1 of 1 [13 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sun Jun 22, 2014 8:31 pm    Post subject: More voltage controlled 40106 fun Reply with quote  Mark this post and the followings unread

Haven't breadboard this yet, but the idea struck me when looking at the MFOS Weird Sound Generator schematic and wondering about how the gate control works and how to put it in my next build.

I had wanted to adapt the WSG core to wire the transistor cv in and the gate straight to the front panel for patching. Part of me thought two cv ins per oscillator was a little over kill too (though I might still go for it!)

Anyway, it struck me that adding a pot between the cv in and the diode would affect the pulse width of the gate and could even end up in cv control. Turn the resistance all the way down for classic WSG gating, and all the way up for pure FM, with things in between possible!

I plan on testing this tomorrow or at the weekend, hopefully have some scope traces and sound clips too.

NOTE: I didn't set the internal impedance of the signal source so the results are not going to be very accurate, though they do hint towards what is possible. I tried setting an impedance of 10k when I used the triangle wave test, but I am skeptical it will be accurate either.


40106 CV TEST.JPG
 Description:
 Filesize:  10.12 KB
 Viewed:  15240 Time(s)

40106 CV TEST.JPG



40106 cv test (tri - impedence adjusted).JPG
 Description:
 Filesize:  118.93 KB
 Viewed:  573 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

40106 cv test (tri - impedence adjusted).JPG



40106 cv test (square).JPG
 Description:
 Filesize:  80.72 KB
 Viewed:  607 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

40106 cv test (square).JPG



40106 cv test (sine).JPG
 Description:
 Filesize:  105.35 KB
 Viewed:  600 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

40106 cv test (sine).JPG


Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sun Jun 22, 2014 8:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

Also, for those of you who are like me and enjoy taking a fake/easy triangle from the cap out put: the output there looks very interesting.

Not sure how to tame the gain differences though. I've been using inverters to amplify the tri out from there, but the much bigger dips down to 0v will need much more headroom...


output from cap.jpg
 Description:
 Filesize:  61.69 KB
 Viewed:  15225 Time(s)

output from cap.jpg


Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sun Jun 22, 2014 10:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

Some more analysis of this: It's not exactly FM, but it's altering adjusting the pulse width of the sync/gate effect. It seems to be doing this by adjusting how fast the cap discharges when the diode is forward biased - which also means it will have less "recovery time" needed to charge up enough to start oscillation again.

The pot also effectively adjusts the knee of the diode, which causes larger and larger ranges of cv input to make the cap charge slower rather than fully discharge.

Not sure if I'm totally right - just speculation
Back to top
View user's profile Send private message
Cynosure
Site Admin


Joined: Dec 11, 2010
Posts: 966
Location: Toronto, Ontario - Canada
Audio files: 82

PostPosted: Tue Jun 24, 2014 8:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool! The one that looks like a saw wave is especially interesting. Can you provide a schematic to get that to work after you test it on breadboard?
Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Tue Jun 24, 2014 6:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

Unfortunately the saw-like output is not possible. It's an error in the simulation caused by me setting the cv source as having an output impedance of 0 ohms! If you check the scale, the simulation calculated it as less than 0.01Vpp.

I'm going to breadboard this Friday because I also want to try the diode the other way for some more CV experimentation but I think I am most likely to go for the WSG-style NPN transistor across the pot for modulation.

I'll post back with results when I get them. I'll try to take sound clips of all of them
Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sat Jun 28, 2014 2:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Lots of pictures and sound samples incoming!

This is going to be part of an article I plan on doing about 40106 oscillators and adding cv to them along with explanations of the hows, whats and and whys.

Overall, if you only want to use square LFOs, then I recommend a 100k pot for the series resistance in front/behind the diode. Good range of sounds available there. If you want to use sine/triangle then a maybe 20k max, but non-digital values have limited use. Not as cool as I hoped but definitely still useful.

There is a threshold point of resistance, over which the output stops being gated and becomes "true" FM. This threshold area is really tiny but could yield some very cool results. I might go back and try pin pointing it and then using a fixed series resistance. Results with analog waveform lfos might be better then.

You can also flip the diode round but it basically sounds the same. Instead, the discharging is slow and the voltage it hits when it gates is high instead of low.


high resistance.jpeg
 Description:
Audio rate cv with fairly high resistance
 Filesize:  16.37 KB
 Viewed:  14941 Time(s)

high resistance.jpeg



40106 wsg diode (cv sweep, 25k resistance).mp3
 Description:
Sweeping a buffered cv source with about 25k resistance inserted. Kind of disappointing. Has made me write this off for non-square LFOs. Very small range of voltages have an effect. Increased resistance makes the range become even smaller

Download
 Filename:  40106 wsg diode (cv sweep, 25k resistance).mp3
 Filesize:  95.48 KB
 Downloaded:  928 Time(s)


40106 wsg diode (cv sweep, no resistance).mp3
 Description:
Buffered CV source sweep with no series resistance. You'll notice that it is either off or the pitch set by the pot. Kind of useless

Download
 Filename:  40106 wsg diode (cv sweep, no resistance).mp3
 Filesize:  71.36 KB
 Downloaded:  1038 Time(s)


40106 wsg diode (slow lfo, increasing resistance).mp3
 Description:
Slow LFO, I sweep the series resistance. Goes from being gated completely, to a nee-naw modulation of the frequency.

Download
 Filename:  40106 wsg diode (slow lfo, increasing resistance).mp3
 Filesize:  362.99 KB
 Downloaded:  1024 Time(s)


40106 wsg diode (audio rate cv, lower carrier, increasing resistance).mp3
 Description:
The most interesting in my opinion. CV and carrier frequency quite close. All that's being adjusted is the series resistance. Really interesting clashing, dissonany sounds here.

Download
 Filename:  40106 wsg diode (audio rate cv, lower carrier, increasing resistance).mp3
 Filesize:  482.72 KB
 Downloaded:  1082 Time(s)

Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sat Jun 28, 2014 2:46 am    Post subject: Reply with quote  Mark this post and the followings unread

There appears to be a maximum of 5 attachments.

Should have mentioned. In all oscilloscope shots - top is square out from the 40106. 2V/div. Bottom is from the cap. 1V/div.


slow charge fast discharge.jpeg
 Description:
This is with the resistance set just around the threshold that pushes it into true FM instead of gating.
 Filesize:  17.47 KB
 Viewed:  14932 Time(s)

slow charge fast discharge.jpeg



resistance increase 2.jpeg
 Description:
Resistance close to reaching the threshold. Notice how the cap charges up to a certain point when the cv is low but can't get high enough to flip the schmitt trigger
 Filesize:  17.49 KB
 Viewed:  14933 Time(s)

resistance increase 2.jpeg



carrier too slow.jpeg
 Description:
No sound because the cap can't charge in time.
 Filesize:  21.54 KB
 Viewed:  14933 Time(s)

carrier too slow.jpeg



carrier just fast enough.jpeg
 Description:
This is when the carrier is *just* fast enough to get one transition in. Very nasal pwm sound
 Filesize:  101.62 KB
 Viewed:  549 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

carrier just fast enough.jpeg



40106 back bias diode cv (audio rate cv, higher freq carrier, no resistance, increasing carier freq).mp3
 Description:
This one is a little different. This is when the carrier frequency starts off too low to charge the cap when the modulation is high. Interesting pwm effects

Download
 Filename:  40106 back bias diode cv (audio rate cv, higher freq carrier, no resistance, increasing carier freq).mp3
 Filesize:  287.66 KB
 Downloaded:  1129 Time(s)

Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sat Jun 28, 2014 2:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Last two


no cv.jpeg
 Description:
For comparison, this is without any CV. Again, top is output, bottom is cap.
 Filesize:  21.9 KB
 Viewed:  14929 Time(s)

no cv.jpeg



high frequency low resistance.jpeg
 Description:
cv modulation with no series reistance
 Filesize:  15.65 KB
 Viewed:  14925 Time(s)

high frequency low resistance.jpeg


Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Sun Jul 27, 2014 10:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Took about a month, but I finished up the article.

I intend it to be a very beginner friendly introduction to circuit analysis


RMR-001 - Simple 40106 oscillator with diode-based CV input.pdf
 Description:

Download
 Filename:  RMR-001 - Simple 40106 oscillator with diode-based CV input.pdf
 Filesize:  739.57 KB
 Downloaded:  2017 Time(s)

Back to top
View user's profile Send private message
synaesthesia



Joined: May 27, 2014
Posts: 291
Location: Germany
Audio files: 85

PostPosted: Mon Jul 28, 2014 12:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Very nice article, commathe. Thanks for posting it. I always wondered why the diode is backwards in this kind of circuit, now I finally understand.
Back to top
View user's profile Send private message
commathe



Joined: Jul 26, 2013
Posts: 153
Location: Beijing
Audio files: 5

PostPosted: Mon Jul 28, 2014 12:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Interestingly, having the diode the other way round actually has the exact same effect. It took me a little bit of time to wrap my head around that myself!
Back to top
View user's profile Send private message
synaesthesia



Joined: May 27, 2014
Posts: 291
Location: Germany
Audio files: 85

PostPosted: Mon Jul 28, 2014 10:37 am    Post subject: Reply with quote  Mark this post and the followings unread

Right, you can switch the oscillator on and off in both cases. But the diode in reverse direction switches it ON with a 1 (Vdd) and OFF with a 0 (GND). I find that more logical.
Back to top
View user's profile Send private message
billsship



Joined: Apr 14, 2013
Posts: 21
Location: Arkansas, USA

PostPosted: Thu Jul 31, 2014 5:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks commanthe for the PDF and the great explanations. It really shows me some new uses for the 40106.
_________________
Vine username: "billsship"
Modulargrid
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: mosc
Page 1 of 1 [13 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use