Modified : oct. 28th. 2008

Saw Animator
En français
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Description

The Saw Animator module is a very interesting module when you whish to get that FAT sound, usually obtained with two or more sawtooth VCOs, but you are short of VCOs. You can get this typical sound with only one sawtooth VCO, thanks to Bernie Hutchins (JAES, 1981). The Digisound 80 has this wonderful module and Scott Bernardi designed a version of its own. The present module is a somehow simplified but yet efficient version. To get the best of this module, it must be used in conjunction with a mixer. I chose not to integrate a mixer within the module in order to benefit from the dry outputs which are very useful when used with a LFO instead of a VCO. When used with a sawtooth LFO and inputing fixed CVs in the MOD inputs, one can achieve some interesting phase shifted modulators such as quadrature modulation. Well the possibilities are numerous and it's up to your imagination...

A basic saw animator patch would be :


Here are a sound samples of the saw-animator using the above patch. These sound clips are 12s long and start with 3s of the raw sawtooth then the ouputs of the module are mixed in.

  •    8' sawtooth, output #1 with slow rate

  •    8' sawtooth,  output #1 with fast rate

  •    8' sawtooth,  output #1 and output 2 both with slow rate

  •    8' sawtooth,  output #1 and output 2 both with fast rate

  •    8' sawtooth,  output #1 with slow rate and output #2 with fast rate

  •    16' sawtooth,  output #1 and output #2 both with slow rate

  •    16' sawtooth,  output #1 and output #2 both with fast rate

Schematic

IMPORTANT NOTE : the circuit has been designed to work with balanced sawtooth signals ranging from -5V to 5V, if you intend to use it with unbalanced sawtooth or different peak to peak voltage you will have to recalculate some resistor values...
Two 100pF capacitors are not shown on this schematic diagram because they are optional. These are to be used to remove spikes at the output. If such spikes are visible, connect these capacitors in parallel to R15 and R30. The PCB was designed with pads for these optional capacitors.

Printed Circuit Board and Component Layout

NOTE : le Circuit imprimé ainsi qu'un kit de composant peuvent être achetés chez Bridechamber
PCB design
Layout





 Download the scematic as a PDF file 
Download the PCB as a PDF file 

WARNING ! The document is formatted to be printed directly on a mylar for photo-etching or a "press & peel" paper. Make sure that when the printed face of mylar is in contact with the copper side of the PCB, the lettering can be read normally.


List of parts and building instructions
reference
 value
 number
U1,U2,U3
 TL074
 3
Q1,Q2
 BC547C
 2
D1,D2,D3,D4
 1N4148
 4
R1,R2
 10 ohm
 2
R17,R32
 1k
 2
R6,R21
 1.5k or 2.2k
 2
R8,R19
 4.7k
 2
R7,R22
 15k
 2
R14,R15,R16,R29,R30,R31 47k
 6
R8,R9,R10,R11,R12,R13,R23,R24,R25,R26,R27,R28 100K 1%
 12
R9,R11 120K
 2
C7,C9
 100pF* optional
 2
C3,C5,C5 100nF 3
C6,C8 2.2µF Wima 63V (or 2x1µF LCC polyester yellow) 2
C1,C2
 22µF/25V electro.
 2
T2,T4
 100K 10 turns trimmer
 2
T1,T3
 250K or 220K 10 turns trimmer 2
LD1,LD2
 yellow LED
 2
P1,P2
 1M rev log potentiometer
 2
Jk1,Jk2,Jk3,Jk4,Jk5,Jk6
 6,5 mm jack socket
 6
Note that in most cases C7 and C9 may be omitted !
For R6 and R21, the value can be selected between 1.5K and 2.2K depending on the brightness and current draw of the LED, try 2.2K and if you find the LED are not bright enaough diminish this value.
Wiring

The wiring diagram is only valid for the latest version of the PCB (june 17th 2007)! 

Front plate
Panel design


 Download the silkscreen mask as a PDF file 


Download the silkscreen mask as a  JPEG file 



Trimming
There are four trimmers to be adjusted. Note that the adjustment procedur is the same for T1 and T3 and for T2 and T4.

Setting of T1 (SHAPE trimmer).
  1. ground the MOD IN #1  input
  2. feed a balanced sawtooth (ranging -5V to 5V) to the SAW IN #1 input
  3. connect an oscilloscope to the  OUTPUT #1 output
  4. check the  shape of the output signal, it soul look either like this  or that
  5.  adjust T1 in order to obtain this
Setting of T2 (BALANCE trimmer)
  1. adjust T2 in order that the output signal is balanced and ranges from -5V to +5V

Unground the MOD IN #1, you must see the sawtooth swaying at the rhythm of the internal LFO

Repeat the same settings to adjust T3 and T4.


References
Bernie Hutchins , JAES 1981 "Analog circuit for Sound Animation", and Electronotes #87
Digisound 80 Modular, Waveform multiplier  
Scott Bernadi's, Obesifier Waveform Animator, OG3 synth
Elektor november 1982, (french version only !)

The DIY builders' gallery
Here are the photographs of the yusynth ARP modules built by other synth geeks around the world.
Thank you  guys for sending me these nice photos.



Name : Louis van Dompselar
Pseudo : Etaoin
Modular project : Casia MS01
Location : Utrecht, Netherlands
Website : www.casia.org/modular

 Name  : Patrick
Pseudo : Baronrouge
Modular project: JHC live lab
Location Toulon, France
Web site : http://myspace.com/patjhc
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