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 Forum index » DIY Hardware and Software » YuSynth
yusynth Sawanimator
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kx



Joined: Dec 05, 2009
Posts: 16
Location: New Zealand

PostPosted: Sun Dec 06, 2009 3:05 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks so much for your reply Smile

Sorry about the pictures before, it looks unbalanced in them, but in reality it is balanced (DC mode, the highest peaks go to +4v and the lowest valleys to -4v).

Can't figure out why it's clipping the tops in the output. If I turn the shape trimmers the other way, the waveform gradually turns into a small square wave.
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yusynth



Joined: Nov 24, 2005
Posts: 1224
Location: France

PostPosted: Sun Dec 06, 2009 3:43 am    Post subject: Reply with quote  Mark this post and the followings unread

I think this is due to the fact one saw (the large one) triggers the convesion but the small one don't, therefore the signal is half converted.
There is nothing to do except submitting a perfectly symmetrical 10Vpp sawtooth.

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yusynth



Joined: Nov 24, 2005
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Location: France

PostPosted: Sun Dec 06, 2009 3:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Check very thoroughly the value of the resistors, R8,R9,R11 and R12 : 100K1%, R14,R15,R16 : 47K, T1 250K, is D2 oriented correctly ?
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kx



Joined: Dec 05, 2009
Posts: 16
Location: New Zealand

PostPosted: Mon Dec 07, 2009 3:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok, to try and pinpoint the problem I've tried these things.

First - instead of using that imperfect saw wave, I've got a saw wave coming from the PC and breadboarded a simple op-amp to amplify it to +/- 5v. - Still the same 'chop off' of the top.

Then I checked the 100k 1% resistors. Took them out and checked their values. In fact, (despite being advertised as 1%) I got some values like 98k and 102k. So I replaced them with much more accurate 100k's with values like 99.9k and 100.0k. Unfortunately this also didn't change the problem.

I couldn't find 250k trimmers, so I had to settle on 200k's. On the forum earlier it was said that 200k would be OK so I tried them. To check, I also tried putting a 47k resistor in series to make a trimpot from 47k - 247k, but it didn't really make any difference either.

the 47k's on the board are also double checked and 1% metal film resistors.

I have the 1N4148 Diodes in their specified positions with the black lines nearest the outer edges of the board...

I'm not sure what to try next, maybe it calls for a replacement TL074? Maybe I should try a LM324 or TL084? I'm running out of things to replace Wink

Thanks again for all your help
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yusynth



Joined: Nov 24, 2005
Posts: 1224
Location: France

PostPosted: Mon Dec 07, 2009 3:28 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Kx

I asked for a check of these components because in 90% of the cases it comes from an error of this kind.

200K trimmers is fine too.

Did you check that the diodes are sane ?
Can you post pictures with the PC enerated sawtooth and for various settings of the trimmer : (five positions : 0%, 25 % 50%, 75%, 100%) ?
For the oscillograms measure them at pin 7 of U3b.

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yusynth



Joined: Nov 24, 2005
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Location: France

PostPosted: Mon Dec 07, 2009 3:33 am    Post subject: Reply with quote  Mark this post and the followings unread

And also make yourself sure that the MOD IN #1 input is connected to the 0V when setting up T1
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kx



Joined: Dec 05, 2009
Posts: 16
Location: New Zealand

PostPosted: Tue Dec 08, 2009 3:35 am    Post subject: Reply with quote  Mark this post and the followings unread

I think I have found the root of the problem. While doing the latest set of tests you suggested, I realized that I wasn't doing the adjustments while looking at the correct output. I was monitoring it from the final output (after the addon mixer).

Here is the input wave : (1 square = 5V)

Posted Image, might have been reduced in size. Click Image to view fullscreen.

After monitoring from pin 7 on U3b, and then pin 1 (U3a) for the balance, I could get the correct swaying waveform when un-shorting mod 1 from ground.

Pin 7 output :

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Pin 1 output :

Posted Image, might have been reduced in size. Click Image to view fullscreen.

I also noticed that the output from pin 1 is inverted from the ouput from pin 7. The problem is, when this shifted, inverted wave is mixed with the original input wave (as is hardwired in my version - I wasn't too worried about quadrature LFO usage) the resultant wave is a square wave, and the effect is the same as PWM on a pulse output, as shown in these pictures :

Posted Image, might have been reduced in size. Click Image to view fullscreen.

=

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Just wondering, is this the correct usage? Maybe I've wired it wrong, since I was expecting to be mixing 2 non-inverted sawtooths.
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yusynth



Joined: Nov 24, 2005
Posts: 1224
Location: France

PostPosted: Tue Dec 08, 2009 5:35 am    Post subject: Reply with quote  Mark this post and the followings unread

I'll do some checking tonight and let you know.
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yusynth



Joined: Nov 24, 2005
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Location: France

PostPosted: Tue Dec 08, 2009 5:49 am    Post subject: Reply with quote  Mark this post and the followings unread

OK I did some simulations and you are right, I did not realize that the waves were in opposite. I will let you know how to modify the add-on board to solve this. In fact I will propose a new add-on board !!!
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nerdware



Joined: Jul 11, 2009
Posts: 91
Location: UK

PostPosted: Tue Dec 08, 2009 9:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Could this be why I hear a beating effect in your demos whenever both animators are used?
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yusynth



Joined: Nov 24, 2005
Posts: 1224
Location: France

PostPosted: Tue Dec 08, 2009 11:28 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Kx

Here is how to fix the add-on board to obtain the right mixture.
I will also update the drawings above with an update version of the add-on PCB.


fix1.gif
 Description:
The red arrows show which tracks must be cut and the blue arrows show the connections to be created with solder bridges
 Filesize:  26.12 KB
 Viewed:  6839 Time(s)

fix1.gif



fix2.gif
 Description:
Once the wrong tracks are cut and the solder bridges (in red) made, solder two 150K resistors as shown
 Filesize:  27.9 KB
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fix2.gif



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yusynth



Joined: Nov 24, 2005
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Location: France

PostPosted: Tue Dec 08, 2009 12:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK I have changed the drawings at the beginning of this thread : new corrected addon-pcb
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kx



Joined: Dec 05, 2009
Posts: 16
Location: New Zealand

PostPosted: Tue Dec 08, 2009 3:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Yves,

Thanks so much for adding those alterations, I applied them to my board this morning, and it works great. Sounds great too! My original 'imperfect waveform' does really well also, and in particular very interesting results come when using input from the 'skew' output of the TH XR-VCO.

Cheers Smile
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Sebo



Joined: Apr 27, 2007
Posts: 539
Location: Argentina

PostPosted: Wed Dec 23, 2009 4:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Yves:
I'm about to start building the Sawanimator module, I etched the PCB and
the add-on PCB. I want to mod it (adding a switch) to have individual otputs
for SAW1 and SAW2, as the add-on is intended for, but also all three signals
in one out (original SAW+SAW1+SAW2), this is handy when you only use
input 1 (a single SAW goes to both processors).
In the new circuit add-on you insert the processed SAW1 in the + input of the
summing OpAmp, and if I want to add SAW2, I have to do it to that node,
I don't know how to do it that way (summing non inverter OpAmp), is there an
easy way to modify the add-on PCB to achieve that?, if not, I will build a little
circuit on stripboard.
Thank you.

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yusynth



Joined: Nov 24, 2005
Posts: 1224
Location: France

PostPosted: Thu Dec 24, 2009 1:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Sebo wrote:

In the new circuit add-on you insert the processed SAW1 in the + input of the
summing OpAmp, and if I want to add SAW2, I have to do it to that node,
I don't know how to do it that way (summing non inverter OpAmp), is there an
easy way to modify the add-on PCB to achieve that?, if not, I will build a little
circuit on stripboard.
Thank you.


You do not need to modify the circuit, send the SAW 1 signal on one lug of the switch, on the other lug of the switch solder a 150K resistor and connect a wire between the resistor and the pad on the add-on board corresponding to the non inverting input of the Opamp.

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Sebo



Joined: Apr 27, 2007
Posts: 539
Location: Argentina

PostPosted: Thu Dec 24, 2009 7:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Yves!!!
One last question:
All three inputs will have a gain of 1 (right?), if all signals are 10Vpp I think
the signal could become too high and clip, should I reduce the gain of inputs?
If so, I did the math using the substractor opamp equation, and I think this
values could work:
R5=200K, R7=R6=R6'(the new input)=100K, and the resistor between the
non inverter input and ground=50K
Thanks a lot for all you help.
Merry Christmas, and the best 2010 to you and your family.

Sebo

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Appliancide*



Joined: Jul 04, 2007
Posts: 119
Location: Paul lives in Thief River Falls

PostPosted: Sun Dec 27, 2009 1:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

If I were going to add a switch for the mixer function, would I just have it disconnect the saw in from the mixer? Or would it be better to bypass the whole mixer circuit?

Thanks,
Paul

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Sebo



Joined: Apr 27, 2007
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PostPosted: Wed Dec 30, 2009 9:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Yves:
Do you read my last post?
I will try the circuit with unity gain and see what happens, if the signal is too
hot I will try to half the gain of the inputs (are my maths OK?).
Thank you again.

> *Appliancide* : I can't understand what you mean.

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Appliancide*



Joined: Jul 04, 2007
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Location: Paul lives in Thief River Falls

PostPosted: Wed Dec 30, 2009 9:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sebo wrote:
> *Appliancide* : I can't understand what you mean.


If I am adding the additional circuitry that mixes the original saw with the shifted saw, where should I add a switch to remove the original saw from the output? Or would a wet/dry pot be better?

Cheers,
Paul

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Appliancide*



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Location: Paul lives in Thief River Falls

PostPosted: Tue Jan 05, 2010 1:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

*Appliancide* wrote:
Sebo wrote:
> *Appliancide* : I can't understand what you mean.


If I am adding the additional circuitry that mixes the original saw with the shifted saw, where should I add a switch to remove the original saw from the output? Or would a wet/dry pot be better?

Cheers,
Paul


Has anyone done this?

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Sebo



Joined: Apr 27, 2007
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PostPosted: Tue Jan 05, 2010 5:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi:
You can add a switch cutting the SAW1 and SAW2 inputs in the Add-On PCB.
I don't see much improvement in a wet/dry pot as the most useful mix between
both signals is 50/50 (at least to me).
I just will add a switch to add Processed SAW2 to Output 1, this is useful when
only one signal is connected as you can get the mix of the SAW1 (input)
plus both Processed SAWs at one output.
I will be working in this module next few days.

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ultrashock



Joined: Dec 10, 2009
Posts: 40
Location: Vienna.AT

PostPosted: Tue Jun 29, 2010 2:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Dear Yves!
Kindly ask you to answer the question concerning your saw animator!
When the RATE pot is at the ZERO level - do we have the CLEAR saw at the output? I mean could we use the ZERO level as the "crossfader" beetween pure saw and "animated"?
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yusynth



Joined: Nov 24, 2005
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PostPosted: Tue Jun 29, 2010 2:54 am    Post subject: Reply with quote  Mark this post and the followings unread

ultrashock wrote:
Dear Yves!
Kindly ask you to answer the question concerning your saw animator!
When the RATE pot is at the ZERO level - do we have the CLEAR saw at the output? I mean could we use the ZERO level as the "crossfader" beetween pure saw and "animated"?


No you misunderstood, the Rate is setting the speed of the internal LFO.
It is not a mixing pot. If you use the add-on board shown above you will have a fixed mix of the raw sawtooth and of the modulated (shifted) ones. If you don't use this board you need an external mixer.

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ultrashock



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PostPosted: Tue Jun 29, 2010 4:09 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you very much for such fast responce!
When I answered about the "rate" knob I meant if the modulation at ZERO rate-level will be so minimal as indistinguishable on ear that we can use is as almost the clear saw
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yusynth



Joined: Nov 24, 2005
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PostPosted: Tue Jun 29, 2010 4:28 am    Post subject: Reply with quote  Mark this post and the followings unread

OK I get your idea, at zero rate the period of modulation is something 5s. Therefore it souns like a sawtooth that would slightly go out of tune.
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