TZFM SAW VCO

[frijitz]

[zthee]

[Sound]

[frijitz]

[frijitz]

[frijitz]

Here are three more Teezer demos.

Demo1 has six sections with different levels of modulation and sync.

Demo2 was made using 1000% dynamic depth modulation. On the long notes you can hear a very slight pitch shift. With soft sync added (second half) the pitch is steady with only a small difference in timbre.

Demo3 is from the same patch as the first two, with the addition of varying levels of modulation and cross coupling.



Ian

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ddtzdemo1.mp3
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Filename:	ddtzdemo1.mp3
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ddtzdemo2.mp3
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Filename:	ddtzdemo2.mp3
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ddtzdemo3.mp3
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Filename:	ddtzdemo3.mp3
Filesize:	2.03 MB
Downloaded:	1406 Time(s)

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[Sound]

[jaidee]

Conversion to +/-15V - which method is best?

I'm about to start building my Teeezer and, I suspect like many, want to incorporate it into my MOTM format system running on +/-15V

I'm conscious that two methods of converting the circuit to operate on +/-15V have ben canvassed.

Dave Brown on his excellent web site describes changes to the values (if memory serves) of 4 resistors and 2 diodes.

On the other hand, Ian, the designer of the circuit, describes a method involving the replacement of the several ferrite beads with various diodes.

I do not have the technical knowledge and insight to be able to weigh up these two alternative approaches, and I wonder whether Dave and/or Ian or indeed anyone else with the technical know-how could indicate the pros and cons of the two methods. Can either be said to be preferable or better??

I'm conscious that Ian's method involves the replacement of all of the ferrite beads which were presumably put into the circuit in the first place for a specific purpose. On the other hand, Dave's approach seems to preserve the ferrite beads. Is the retention of the ferrite beads an advantage, or I am simply demonstrating my complete lack of insight here??

Any guidance would be very much appreciated.

[Tasmanian Alkaloid]

[frijitz]

I haven't tested either method extensively, since I always use 12 V supplies, but I think either method is fine. I worked with Dave on his changes and his method seems to thoroughly address all the areas that need modification, although I didn't do a direct comparison with mine. My method potentially provides improved power supply regulation and decoupling, since it actually provides local regulation of all the supply voltages, and additionally it can be applied to any 12V module that needs be adapted to 15V. The beads' purpose is to choke off high frequency noise on the supply lines. If for some reason this still turns out to be a problem for you, you can always put beads on the supply lines external to the board.



Ian

[Sound]

Well well well... I have space in the front panel for two extra jacks... and I'm thinking in:

1)One output of the exponential sum, that seems useful if I want to control the two Teezers (mine is dual) with the same value.
Due I would like to have a 1K resistor at the output and control over the gain because accurate 1V/Octave tracking, I will put two inverting amplifiers at serial connected in the node before the summing amplifier A1a.

2)Another sine output, in order to have one sine to modulate, and other for audio output for example.
I would do it with a voltage follower but in order to make the adds according with the accurate of the circuit, Do I need a compensating capacitor for stability in the voltage follower? If yes, Is it possible to put a compensating capacitor in a voltage follower? where? in the output to ground?
Or is better two inverting amplifiers in serial?... mmm with an extra switch I will have the sine ore the inverted sine...

Do you see these mods useful? other suggestions? all is correct?

Thaaaaaaaaaaanks!

[/mr]

[Sound]

Thanks for u answer /mr!

[/mr]

[Sound]

Ah yes, but I meant a buffer for each output. You are suggesting to put two jacks a the A8 otput, isnt it?

[/mr]

[Sound]

Thanks /mr, this simplifies the work, and I can start with this sure. I will take some measures and lets see. I was on the idea that an output with its own buffer opamp is a more accurate job.

Today, I'll make the front panel

[/mr]

[blue hell]

[Sound]

Thanks Blue, I thought that I could lose amplitude like in passive multiples splitting signals and maybe isolation within the two outputs. Finally, I ll do the copy of the sine just wiring other jack.

Prototype frontpanel/hardware for dual eurorack advancing.

[v-un-v]

I apologise if this has already been answered elsewhere, but can the Teezer operate at subsonic frequencies too?- Like an LFO is what I mean.

[frijitz]

[Sound]

Ok Ok Ok,

Just finished the prototype frontpanel and hardware. Dual Teezer.
It has a coarse and a fine pots by the initial pot, an extra DC coupled Linear FM IN, an extra exponential sum out, and an extra sine output.
Oeoeoeoeoe!

Edited pictures.

[Sound]

The dual teezer is working and sounds amazing.

I have some questions

1) As you can see in the picture, there is a pulse before the ramp starts.
This pulse is in the two teezer.
Only when the Initial control is in the negative range.
The diodes D12 and D13 were matched at cents of volt.
What could be?

2)The fact that I added a Fine Initial pot that pass through a 1MΩ resistor to opamp A3 means that when the two pots (Coarse Initial and Fine Initial) are fully CW is like I'm sending +5,5V.
For send exactly +5V I should put the Fine Initial pot at centre position, thing that is not precise.
So, my question is, Do I need the option of send 5V exactly to A3?


Edited pictures.

[frijitz]