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rene_schmitz
Joined: Oct 27, 2013 Posts: 16 Location: germany
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Posted: Fri Nov 08, 2013 4:34 am Post subject:
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isak wrote: |
1. why R27 is a Pot? is it for the amount of the sync?
2. Can I use the sync parts as is in the original scheme?
3. Connected To pin 3 of the 4069, right?
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This is some kind of soft sync scheme, and R27 is to set the strength of the sync. You can combine these parts with the original schematic, if that's what you mean.
isak wrote: |
4. I will want 2 or even 3 of this vco, if I want to sync between them I will need a sync out, is it possible to do, if yes how?
5. What would be the Vpp output?
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You could use the sync with a saw or pulse from another VCO.
Cheers,
René _________________ My site: http://www.schmitzbits.de |
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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Posted: Fri Nov 08, 2013 6:33 am Post subject:
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Thanks Renè.
I think I got all the answers I wanted
Cheers,
Isak E. _________________ http://www.myspace.com/mgmtrance |
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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Posted: Mon Nov 11, 2013 9:55 am Post subject:
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Hi flab,
Nice one!
Can you post the layout with parts please?
Cheers _________________ http://www.myspace.com/mgmtrance |
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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Posted: Mon Nov 11, 2013 10:54 am Post subject:
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Hi there Isak,
give me a couple of days cause i have to change few things
also I'll update this layout to a dual vco and use the illustrator to give it a nice touch
I ll also post a schem with mods.
cheers |
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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Posted: Thu Nov 14, 2013 8:56 am Post subject:
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cheers Isak ,
I ll have a look soon -
also if you thinking of etching it , well dont - there are three mistakes for sure + do youthink i should put sth like a protection frrom power to 071 , if yes then please give me a tip mate |
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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Posted: Thu Nov 14, 2013 9:40 am Post subject:
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i am using Rene's buffering amp at the above schem - ok i ll start correcting the layout |
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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Posted: Thu Nov 14, 2013 12:11 pm Post subject:
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Yes, I see that but I don't think you'll need the op amp after the saw buffering. _________________ http://www.myspace.com/mgmtrance |
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rene_schmitz
Joined: Oct 27, 2013 Posts: 16 Location: germany
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Posted: Sun Nov 17, 2013 8:22 am Post subject:
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@flab: You could simply use a unity gain opamp follower for the buffer. I.e. output connected back to - input. And I would make the pads of resistors etc on that layout somewhat larger, makes it easier to solder in the end. Space is available.
@isak: The buffer is needed because the signal at the mix pot wiper has a relatively high impedance, so you'll loose signal amplitude when it is loaded. _________________ My site: http://www.schmitzbits.de |
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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Posted: Sun Nov 17, 2013 8:33 am Post subject:
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Hi Rene.
as i understand we need to buffer the signal before the mix pot, not after,should we buffer the signal before and after the mix pot?
cheers,
Isak E. _________________ http://www.myspace.com/mgmtrance |
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rene_schmitz
Joined: Oct 27, 2013 Posts: 16 Location: germany
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Posted: Sun Nov 17, 2013 8:42 am Post subject:
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Hi Isak,
Yes, the sawtooth is brought up to the same amplitude first with the "sawtooth buffer amp". And after the mix pot, you should buffer it again.
So it is buffered twice, but the sawtooth amps main purpose now is to match up the amplitudes. (Just as flab has drawn it in the schematic)
Cheers,
René _________________ My site: http://www.schmitzbits.de |
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isak
Joined: Dec 13, 2009 Posts: 847 Location: Israel
Audio files: 18
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Posted: Sun Nov 17, 2013 8:56 am Post subject:
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Hi Rene.
i understand, thank you for the input!
sorry flad, it seems i was wrong
cheers,
Isak E. _________________ http://www.myspace.com/mgmtrance |
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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emmaker
Joined: Aug 10, 2007 Posts: 12 Location: Portland, OR
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Posted: Wed Nov 20, 2013 2:50 pm Post subject:
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Has anyone taken the 3 inverters used to do the wave shaping and used them for a second oscillator?
Wondering if there are issues like them syncing together or not working correctly.
Thanks
Jay S. |
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rene_schmitz
Joined: Oct 27, 2013 Posts: 16 Location: germany
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Posted: Tue Nov 26, 2013 5:56 am Post subject:
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emmaker wrote: | Has anyone taken the 3 inverters used to do the wave shaping and used them for a second oscillator?
Wondering if there are issues like them syncing together or not working correctly.
Thanks
Jay S. |
I've never tried it, and I wouldn't recommend it either. There is already an ever so slight interaction between the PWM and the oscillator frequency, resulting in a tiny detuning while turning the PW pot/or external PWM. (It seems that the internal bonding wires, and their resistance cause this.) I guess that two oscillators in the same package will interact similarly. Which should lock the two frequencies together.
The 4069 is really cheap. Just get two. If you don't want the pulse, just tie the unused gate inputs to gnd.
Cheers,
René _________________ My site: http://www.schmitzbits.de |
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J3RK
Joined: Jun 05, 2006 Posts: 123 Location: Seattle
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Posted: Tue Nov 26, 2013 12:22 pm Post subject:
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rene_schmitz wrote: | I've never tried it, and I wouldn't recommend it either. There is already an ever so slight interaction between the PWM and the oscillator frequency, resulting in a tiny detuning while turning the PW pot/or external PWM. (It seems that the internal bonding wires, and their resistance cause this.) I guess that two oscillators in the same package will interact similarly. Which should lock the two frequencies together.
The 4069 is really cheap. Just get two. If you don't want the pulse, just tie the unused gate inputs to gnd.
Cheers,
René |
Hi Rene,
I ran into this with one of my own VCO designs recently, and there were a couple of causes for it. (not 4069 based) One was that I didn't have enough bulk capacitance on the board, so I increased the power filtering caps. The other was that I was using low R resistors on the power rails, which were causing some current fluctuations under certain circumstances, the main one being while adjusting PWM. It would pull the pitch up and down very slightly. I replaced those resistors with ferrites and the problem went away completely.
I'm wondering if the same could be true on this design, or if maybe adding some extra capacitance might help mitigate it a bit.
Just a thought anyway. |
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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Posted: Wed Nov 27, 2013 7:36 am Post subject:
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i did build the vco four days ago at a strip board so i haven't yet tested the pcb uploaded above the other day -
I am getting a funny thing from the vco though - every time I power up the module you can hear it to tuning up more than an oct needs more than 10sec to get almost stably. and then when im trying it to send CV some times it responds and sometimes not-
Could that be that i use a bad quality bc548? |
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rene_schmitz
Joined: Oct 27, 2013 Posts: 16 Location: germany
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Posted: Wed Dec 04, 2013 7:19 am Post subject:
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Hi flab,
I've never noticed this behaviour. Are you sure your circuit is ok?
Does it correspond with the heat up of the 4069?
Cheers,
René _________________ My site: http://www.schmitzbits.de |
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Audiobubble
Joined: Dec 09, 2013 Posts: 1 Location: Liège (Belgium)
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Posted: Mon Dec 09, 2013 7:03 am Post subject:
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Hi Folks,
It's my first post here and after a lot of reading here and there I built rene's VCO on perfboard. It's my first step in sdiy.
It seems to work fine, but the level of the saw output is really really low.
So i built the buffered output found on the rene's documents. The level is higher now but still really lower than the pulse output.
Is it a normal beaviour ?
The vco is powered +12v/-12V and i use 2n3904 for npn (for the buffered output too) and 2n3906 for pnp.
Thanks for the help,
cheers,
Guillaume |
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flab
Joined: Feb 13, 2012 Posts: 65 Location: Glasgow
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Posted: Mon Dec 09, 2013 9:58 am Post subject:
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hi Rene ,
it is obvious that is my fault and not your circuits - i ll start from beginning soon , and it does correspond to the 4069 heat , hmmm , never mind i ll start again , cheers |
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airfrankenstein
Joined: Jan 10, 2010 Posts: 62 Location: france
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Posted: Wed Feb 12, 2014 10:50 am Post subject:
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Flab, have you gotten a chance to verify your pcb layout? |
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