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WIGGLING 'LITE' IN GUEST MODE

Working on a Teezer VCO
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Working on a Teezer VCO
Haralds:Werk
I started to work on a Teezer VCO based on the documentation from Ian Fritz, March 2010. First goal is putting all parts on a max 10x10cm PCB and get it running. From there I want to explore a deeper understanding on how it works. And then may be make some changes. The power distribution with looks quite complicated with the different nets. And I want or try different OpAmps as well. The main goal is to build a version with the PCB's stacked and in parallel to the front panel.

But here is my question:

Is it OK to post schematics and layouts here in the forum? The original is from Ian Fritz and all credits go to him. I don't want to offend anyone or brake some rules. This is a strictly DIY project. No commercial interest.

Meanwhile a picture where I am:

sduck
Please contact Ian directly before posting more here - he's on the forum, user name frijitz. And in his case, posting schematics isn't usually allowed, but you should contact him and make sure.
Haralds:Werk
sduck wrote:
Please contact Ian directly before posting more here - he's on the forum, user name frijitz. And in his case, posting schematics isn't usually allowed, but you should contact him and make sure.


Thank you for the reply. I have already received a PM that point me to a conflict in the past. Of course I will not post any schematics without permission.
frijitz
Haralds:Werk wrote:
I started to work on a Teezer VCO based on the documentation from Ian Fritz, March 2010. First goal is putting all parts on a max 10x10cm PCB and get it running. From there I want to explore a deeper understanding on how it works. And then may be make some changes. The power distribution with looks quite complicated with the different nets. And I want or try different OpAmps as well. The main goal is to build a version with the PCB's stacked and in parallel to the front panel.

But here is my question:

Is it OK to post schematics and layouts here in the forum? The original is from Ian Fritz and all credits go to him. I don't want to offend anyone or brake some rules. This is a strictly DIY project. No commercial interest.

Hello, and thanks for the interest!

I have decided to no longer protect this version of the design, as it is out of production. So have at it. Please keep us informed on your progress, and feel free to ask any questions.

The power traces were separated, and subregulated power sources were used to try to minimize crosstalk, especially coupling with the modulation source.

Additionally, I suggest adding 470pF caps across the LM311 inputs.

Ian
Haralds:Werk
frijitz wrote:
Haralds:Werk wrote:
I started to work on a Teezer VCO based on the documentation from Ian Fritz, March 2010. First goal is putting all parts on a max 10x10cm PCB and get it running. From there I want to explore a deeper understanding on how it works. And then may be make some changes. The power distribution with looks quite complicated with the different nets. And I want or try different OpAmps as well. The main goal is to build a version with the PCB's stacked and in parallel to the front panel.

But here is my question:

Is it OK to post schematics and layouts here in the forum? The original is from Ian Fritz and all credits go to him. I don't want to offend anyone or brake some rules. This is a strictly DIY project. No commercial interest.

Hello, and thanks for the interest!

I have decided to no longer protect this version of the design, as it is out of production. So have at it. Please keep us informed on your progress, and feel free to ask any questions.

The power traces were separated, and subregulated power sources were used to try to minimize crosstalk, especially coupling with the modulation source.

Additionally, I suggest adding 470pF caps across the LM311 inputs.

Ian


Hello Ian,

thank you. That is very generous. I wanted to PM you today but you already answered my questions. Decoupling was the first to come to mind when looking at the power traces. And thanks for the advice to use additional caps at the LM311 inputs. I don't expect my design to work properly on the first shot. This is my starting point. It will take some iteration. I'll post my progress here.

I really appreciate you work. BTW I used a suggestion from you in an early EN issue for building a pitch to voltage converter. My main instrument is the Shakuhachi. And as a woodwind (bamboo :-) ) player I always wanted to join this two worlds. My Shakuhachi 2 Synth project works quite well and is tested by my Shakuhachi teacher as working. It is still modular but I am working on a more portable standalone solution. You can find it
here.
Haralds:Werk
All components squeezedd on 10x10cm. PCB ordered.

Haralds:Werk
The PCB for my first attempt arrived today

Haralds:Werk
After some debugging I got it working. Here is a pic from the trough zero modulation.



But I still have to fight an strange error with the down ramp. Between 200Hz and 4kHz I can see this short pulse of about 4 microS. It shows up at the same time as the reset pulse from the comparator. Some sort of timing problem. Or the canceling of the charge injection is not working correctly here. Maybe some capacitive coupling. It is not audible though. I will look in this with a new, corrected PCB. The up ramp is fine.

frijitz
Haralds:Werk wrote:
But I still have to fight an strange error with the down ramp. Between 200Hz and 4kHz I can see this short pulse of about 4 microS. It shows up at the same time as the reset pulse from the comparator. Some sort of timing problem. Or the canceling of the charge injection is not working correctly here. Maybe some capacitive coupling. It is not audible though. I will look in this with a new, corrected PCB. The up ramp is fine.

Yep, that can happen. confused

For proper operation, the up and down ramps need very close symmetry. First the Zeners D12/13 need to be very closely matched. If they are, and the Saw Symmetry adjustment won't get rid of the glitch, then the charge injection cap C6 may need to be changed. In Dave Brown's excellent writeup, he found 33 pF to work OK.

Good job on getting the unit to work -- shouldn't be too hard to get rid of the glitch.

Ian
Haralds:Werk
frijitz wrote:
Haralds:Werk wrote:
But I still have to fight an strange error with the down ramp. Between 200Hz and 4kHz I can see this short pulse of about 4 microS. It shows up at the same time as the reset pulse from the comparator. Some sort of timing problem. Or the canceling of the charge injection is not working correctly here. Maybe some capacitive coupling. It is not audible though. I will look in this with a new, corrected PCB. The up ramp is fine.

Yep, that can happen. confused

For proper operation, the up and down ramps need very close symmetry. First the Zeners D12/13 need to be very closely matched. If they are, and the Saw Symmetry adjustment won't get rid of the glitch, then the charge injection cap C6 may need to be changed. In Dave Brown's excellent writeup, he found 33 pF to work OK.

Good job on getting the unit to work -- shouldn't be too hard to get rid of the glitch.

Ian


Thanks Ian. I have corrected some mistakes I made on the PCB. Now waiting for the next run.
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