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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Sun Oct 28, 2012 6:22 am Post subject:
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my observations so far (no conclusions):
it is true, while all other outputs are 10Vpp, the sine is way weaker on my build - just 6.4Vpp when trimmed round nicely!
when i built the VCO i had no TL074 on hand, so i used TL084 instead. nevertheless, in regards to output voltage swing these parts are speced to be the same!?
today i replaced both TL084 with LM324, and now i get a nice 10Vpp sine.
i wished i could try a TL074, alas, i have only tons of TL072 in my drawer... _________________
cheers,
matthias
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Big Boss at fonitronik
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
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Posted: Sun Oct 28, 2012 2:09 pm Post subject:
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Interesting result matthias.
thanks _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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AlasdairMoons
Joined: Dec 03, 2011 Posts: 105 Location: East-Belgium
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Sun Oct 28, 2012 2:55 pm Post subject:
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thank you for your kind offer! great comradeship here!
but no need to rush. will order a batch this week along with other stuff. _________________
cheers,
matthias
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Big Boss at fonitronik
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Thomas_Henry
Joined: Jul 24, 2009 Posts: 170 Location: N. Mankato, MN
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Posted: Sun Oct 28, 2012 3:22 pm Post subject:
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Hello Fonik,
Just a quick comment: the sine is buffered by one of the Darlington pairs in the LM13700. Thus, if the triangle wave is a legit 10Vpp, then changing op-amps elsewhere shouldn't influence the sine. A more likely place to look is at the resistors surrounding the OTA.
By the way, changing the sine trimmers will change the output amplitude. Remember, the "best looking" sine is not necessarily the "best-sounding" (i.e., lowest distortion) and may lower the amplitude due to too much curve-bending. Use your ears only if you haven't already done so, and only afterwards look at the scope.
Scott and I spent a lot of time going back and forth on setting the resistor values to give 10Vpp with lowest distortion. But I suppose LM13700 variation could change this. I don't have the circuit on my breadboard anymore, but maybe Scott does for confirmation.
And, hey, how about that sync!
Thomas Henry |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
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Posted: Sun Oct 28, 2012 4:05 pm Post subject:
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Thomas_Henry wrote: | And, hey, how about that sync! |
i thought even my short demo reflects my excitement. i personally favor the timbres of the triangle and saw outputs when synced. holy moly! _________________
cheers,
matthias
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Big Boss at fonitronik
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diablojoy
Joined: Sep 07, 2008 Posts: 809 Location: melbourne australia
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Posted: Sun Oct 28, 2012 4:33 pm Post subject:
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Quote: | i personally favor the timbres of the triangle and saw outputs when synced. holy moly! |
wholly agree the sync really is wonderful.
makes me wish i could afford 6 or even 12
but my backlog is ridiculous enough as it is
perhaps if you have any LF4xx series in stock ?
I tend to use them inplace of TL0xx now.
better specs and almost unkillable
I had 3 survive reverse polarity totally unscathed the other week on a prototype board which is now working fine after fixing the offending tracks
never had a TL0xx series chip manage that trick and actually that is how i realised my error , as the top of a tl072 that is embedded in my ceiling is still pointing it out to me.
lesson learnt : dont trust the standard eagle parts library and always do your own - the LF442 has its power pins reversed in the eagle library
curtesy perhaps of someone with a slightly twisted sense of humour ? _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any |
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sonic
Joined: Dec 02, 2010 Posts: 106 Location: Victoria BC
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Posted: Sun Oct 28, 2012 5:16 pm Post subject:
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Only just discovered this, and oh lordy! This sounds GREAT! I have all the parts already. Count me in for 2 PCBs, though I'm so excited I want to say more! |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
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Posted: Sun Oct 28, 2012 6:06 pm Post subject:
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Quote: | as the top of a tl072 that is embedded in my ceiling is still pointing it out to me. |
I think I published the picture of the top of a TL07[1 or 2] that went popcorn on me. Entirely my own fault though. |
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AlasdairMoons
Joined: Dec 03, 2011 Posts: 105 Location: East-Belgium
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Mon Oct 29, 2012 2:56 pm Post subject:
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in this special case i
1st: feed the 1V/oct input of the 555-VCO with a cv sequence. then
2nd: i apply a square wave from another VCO (fixed freq and PW) to the sync input (gives this robotic synced sound). then
3rd: i apply a small amount of a triangle from a LFO to the exponential FM input (gives you these phasing overtones). _________________
cheers,
matthias
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Big Boss at fonitronik
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Silesius
Joined: Feb 12, 2010 Posts: 65 Location: Berlin
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Posted: Mon Nov 19, 2012 3:09 am Post subject:
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Hi, I'm thinking on building a couple of this vco's. I've been waiting for the pcb's, but I'm not sure if this is going to happen, so I think I'm going to try a stripboard version. The circuit is simple enough, and I think I am able to do it, if I am careful.
But I've never tried to match transistors, and I think it's a little too much for me. It would be nice to just buy some matched pairs. I've been looking a little on ebay and some online shops, but I can't find matched 2n3906's. So my question is: is there any easy substitution for that? Would any general purpose matched pnp's work here (let's say a bc557)? Or something like the ssm2220?
Any suggestions would be very appreciated. Thanks! |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Mon Nov 19, 2012 10:38 am Post subject:
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it will happen, the new prototype PCBs are ordered allready and should arrive early in december.
re transistors. i did not match mine, i just used two from the same batch. as you can hear in the demo vid this is sufficient, i don't can show you any measuremtns, though. _________________
cheers,
matthias
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Big Boss at fonitronik
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Silesius
Joined: Feb 12, 2010 Posts: 65 Location: Berlin
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Posted: Mon Nov 19, 2012 11:49 am Post subject:
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Thanks, fonik. I think I'll wait for the pcb's in that case. You can count me in for two of them. By the way, is there any chance to get the TH controller LFO pcb's as well? Maybe at the same time? That would be great. |
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sonic
Joined: Dec 02, 2010 Posts: 106 Location: Victoria BC
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Posted: Mon Nov 19, 2012 6:09 pm Post subject:
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Quote: | the new prototype PCBs are ordered allready and should arrive early in december. |
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AlasdairMoons
Joined: Dec 03, 2011 Posts: 105 Location: East-Belgium
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JingleJoe
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
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Posted: Fri Nov 30, 2012 3:33 am Post subject:
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ungleichklang wrote: | fonik wrote: |
i wished i could try a TL074, alas, i have only tons of TL072 in my drawer... |
I have some lying here ... do you need them now?? could make a letter monday mornin .. |
I was going to suggest that too but then I saw the timestamp
I don't know if I ever mentioned but this VCO is really appealing to me be- oh wait, I already said it in the first post _________________ As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"
Green Dungeon Alchemist Laboratories |
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oculus
Joined: Oct 30, 2011 Posts: 35 Location: Iceland, Reykjavik
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Posted: Sun Dec 09, 2012 7:56 am Post subject:
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fonik wrote: | it will happen, the new prototype PCBs are ordered allready and should arrive early in december.
re transistors. i did not match mine, i just used two from the same batch. as you can hear in the demo vid this is sufficient, i don't can show you any measuremtns, though. |
hi there matthias. are you using 12volts or 15V?
has anybody made this using 12volts?
Thanks. Fridfinnur |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Sun Dec 09, 2012 12:19 pm Post subject:
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you can run it on 12V without any changes. _________________
cheers,
matthias
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Big Boss at fonitronik
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oculus
Joined: Oct 30, 2011 Posts: 35 Location: Iceland, Reykjavik
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Posted: Sun Dec 09, 2012 3:27 pm Post subject:
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fonik wrote: | you can run it on 12V without any changes. |
nice thank you, i guess thereĀ“s no way out, i have to make one. btw thanks for posting the video it sounds really nice |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Sat Jan 05, 2013 2:45 pm Post subject:
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re sine output.
powering the module from +/-12V, i had to lower R27 to 33k in order to get the 10vpp amplitude on the sine wave.
my recommendation for any build, even 15V systems:
lower R27 to 33k, raise R24 trimmer from 25k to 50k (or even 100k multiturn). then you should be fine. _________________
cheers,
matthias
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Big Boss at fonitronik
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stubbyfex
Joined: Sep 08, 2009 Posts: 8 Location: Denver, Colorado
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Posted: Sat Jan 19, 2013 1:40 pm Post subject:
WTB 555 VCO PCB |
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Hello!
I'd like to order one of the 555 VCO PCB.
I'm using Thomas Henry's VCO-1 currently, with good results.
My synth is a homemade 5MU style.
Thanks very much. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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MrZ
Joined: Jan 14, 2013 Posts: 11 Location: Finland
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Posted: Mon Mar 18, 2013 10:54 pm Post subject:
VCO-555 bleeding |
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Hi,
This vco sounds great but I get bleeding to other modules thru the power rails.
Any idea for a solution ? |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
Audio files: 23
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Posted: Tue Mar 19, 2013 1:08 am Post subject:
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bleeding is an issue that comes up in the forums from time to time for all kind of VCOs.
1st check your PSU. do you see a voltage drop? in other words, can it deliver enough current? _________________
cheers,
matthias
____________
Big Boss at fonitronik
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