Category Archives: Waveshaper

Quad Ringmodulator

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Quad Ringmodulator: Front view
Quad Ringmodulator: Front view

This is the 12V Euro version of my NGF dual version. It uses the now obsolete LM1496 balanced modulator -demodulator. But you can still source them and I have some in my stock. So I decided to make a PCB and module. I started with the original Elektor Formant schematic published in “Formant Erweiterungen” p35ff. I left out the microphone and envelope follower part because I already have such modules. I have added input buffers and raised the signal level to my 10Vpp used throughout my system.

Specs and features

  • Quad Ringmodulator
  • 10Vpp input and output
  • Runs on +/-12V and +/-15V
  • Power consumption around 70mA each rail

The documentation and the Gerber files for download can be found in my website.

Quad Ringmodulator: Schematic control board
Quad Ringmodulator: Schematic control board
Quad Ringmodulator: Schematic main board
Quad Ringmodulator: Schematic main board
Quad Ringmodulator: Populated control PCB
Quad Ringmodulator: Populated control PCB
Quad Ringmodulator: Populated main PCB
Quad Ringmodulator: Populated main PCB
Quad Ringmodulator: Back view
Quad Ringmodulator: Back view
Quad Ringmodulator: Side view
Quad Ringmodulator: Side view

Multi Phase Waveform Animator

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Multi Phase Waveform Animator: Front view

This is my take on a multi phase waveform animator as described in EN#87 pg.3 ff by Bernie Hutchins. This module takes a single sawtooth waveform and then uses nine phase shifters to provide shifts from 0° to 360°. These shifts are controlled each by an independent oscillator which operates on a frequency of about 0.01Hz to 1.0Hz. The nine shifted waveforms are then mixed back together, along with original, to a composite sound. The volume of all phase shifted waveforms and the original are controlled with potentiometers. So you can dial in any amount of animation you like. You can choose from a variety of frequencies for the phase shifters. The method used here is described in EN#40 by Ralph Burhans. Ralph found that if you space frequencies at the fifth root of 2.1, you get no harmonic overlap over a 10 octave range. This is important because we don’t want to produce patterns which will repeat and be detected by our ears to keep the sound animated. As you can see in the screenshots you can use this module for other waveforms as well.

Specs and features

  • Nine independent phase shifters
  • Volume control for all phase shifted waveforms
  • Takes a lot more then only sawtooth inputs
  • Runs on +/-15V and +/-12V
  • Power consumption around 35mA each rail

The documentation and the Gerber files for download can be found in my website.

Multi Phase Waveform Animator: Schematic control board
Multi Phase Waveform Animator: Schematic main board 01
Multi Phase Waveform Animator: Schematic control board 02
Multi Phase Waveform Animator: Populated control board
Multi Phase Waveform Animator: Populated main board
Multi Phase Waveform Animator: Populated main board
Multi Phase Waveform Animator: Back view
Multi Phase Waveform Animator: Side view

Trapezoid quadrature through zero VCO (Euro version) with waveshapers

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Trapezoid quadrature through zero VCO with waveshapers: Front
Trapezoid quadrature through zero VCO with waveshapers: Front

This is my third take on the Trapezoid VCO core designed by Don Tillman. My first implementation for a 15V banana system with separate waveshaper can be found here. My second implementation for a 15V banana system with integrated waveshaper can be found here.This time I moved on to the 12V Eurorack format. The core is still based on the original design from Don (used with permission). I found the original article and schematic about the Trapezoid VCO on Don Tillman’s site (Link to original article from 19 July 2003). The article consists off three parts with the core implementation in part 2. I kept the basic idea and changed nearly everything else. I use an other exponentiator scheme and temperature stabilization. Another reference voltage device is used. A octave switch is added. And quadrature square outputs are implemented. As well as the additional waveforms triangle, sine, ramp up, ramp down and pulse.

Specs and features

  • Trapezoid quadrature output
  • Square quadrature output
  • Triangle quadrature output
  • Sine quadrature output
  • Pulse output, 0deg, 90deg
  • Ramp up output 0deg, 90deg
  • Ramp down output 0deg, 90deg
  • Octave switch
  • Through zero modulation
  • PWM input
  • V/Oct, FM log and trough zero CV input
  • Temperature compensated
  • Fine frequency setting
  • Runs on +/-15V and +/-12V
  • Power consumption around 110mA each rail

The documentation and the Gerber files for download (link) can be found in my website (link).

Trapezoid quadrature through zero VCO with waveshapers: Schematic control PCB
Trapezoid quadrature through zero VCO with waveshapers: Schematic control PCB
Trapezoid quadrature through zero VCO with waveshapers: Schematic main PCB
Trapezoid quadrature through zero VCO with waveshapers: Schematic main PCB
Trapezoid quadrature through zero VCO with waveshapers: Schematic main PCB
Trapezoid quadrature through zero VCO with waveshapers: Schematic main PCB

J. Donald Tillman did an excellent job describing the core of his Trapezoid VCO. Please refer to the original article as linked above. Don Tillman gave me the advice to use only two capacitors in the core. The exponentiator I use is a well known and a classical design. You can find many description of it out there. The rest is straight forward.

Trapezoid quadrature through zero VCO with waveshapers: Populated control PCB
Trapezoid quadrature through zero VCO with waveshapers: Populated control PCB
Trapezoid quadrature through zero VCO with waveshapers: Populated main PCB
Trapezoid quadrature through zero VCO with waveshapers: Populated main PCB
Trapezoid quadrature through zero VCO with waveshapers: Back view
Trapezoid quadrature through zero VCO with waveshapers: Back view
Trapezoid quadrature through zero VCO with waveshapers: Side view
Trapezoid quadrature through zero VCO with waveshapers: Side view
Trapezoid quadrature through zero VCO with waveshapers: Screenshot trapezoid wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot trapezoid wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot square wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot square wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot sine wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot sine wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot triangle wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot triangle wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot pulse wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot pulse wave out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot triangle through zero out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot triangle through zero out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot trapezoid through zero out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot trapezoid through zero out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot trapezoid through zero out
Trapezoid quadrature through zero VCO with waveshapers: Screenshot trapezoid through zero out

Trapezoid quadrature VCO through zero (flat version) with waveshapers

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Trapezoid quadrature VCO through zero (flat version) with waveshapers
Trapezoid quadrature VCO through zero (flat version) with waveshapers: Front view

This is my second take on the Trapezoid VCO designed by Don Tillman. My first implementation can be found here. This time I mounted the PCB’s parallel to the front to save space and integrated the wave shapers. The core is still based on the original design from Don (used with permission). I found the original article and schematic about the Trapezoid VCO on Don Tillman’s site (Link to original article from 19 July 2003). The article consists off three parts with the core implementation in part 2. I kept the basic idea and changed nearly everything else. I use an other exponentiator scheme and temperature stabilization. Another reference voltage device is used. And quadrature square outputs are implemented. As well as the additional waveforms triangle, sine, ramp up, ramp down and pulse.

Specs and features

  • Trapezoid quadrature output
  • Square quadrature output
  • Triangle quadrature output
  • Sine quadrature output
  • Pulse output, 0deg, 90deg
  • Ramp up output 0deg, 90deg
  • Ramp down output 0deg, 90deg
  • Through zero modulation
  • PWM input
  • V/Oct, FM log and trough zero CV input
  • Temperature compensated
  • Coarse and fine frequency setting
  • Runs on +/-15V and +/-12V
  • Power consumption around 135mA each rail

The documentation and the Gerber files for download can be found in my website.

Trapezoid quadrature VCO through zero (flat version) with waveshapers: Back view
Trapezoid quadrature VCO through zero (flat version) with waveshapers: Back view

Quad waveshaper for trapezoid quadrature thru zero VCO

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Quad waveshaper for trapezoid quadrature VCO
Quad waveshaper for trapezoid quadrature VCO

This is the waveshaper for my Trapezoid quadrature through zero VCO. It gives the quadrature outputs for triangle, sine and the outputs for saw (ramp up, ramp down) and pulse. To use it you need my Trapezoid quadrature VCO. The waveshaper has no external input for waves, it is internally connected with the Trapezoid quadrature VCO

Specs and features

  • Four triangle quadrature outputs
  • Four sine quadrature outputs
  • Two saw (ramp up) outputs 90° apart
  • Two saw (ramp down) outputs 90° apart
  • Two pulse outputs 90° apart
  • Voltage controlled pulse width
  • Runs on +/-15V and +/-12V
  • Power consumption around 50mA each rail

The documentation and the Gerber files for download can be found in my website .

Schematic 01 quad waveshaper for quadrature thru zero VCO
Schematic 01 quad waveshaper for quadrature thru zero VCO
PCB quad waveshaper for quadrature thru zero VCO
Schematic 02 quad waveshaper for quadrature thru zero VCO

The triangle waves are created by algebraically averaging two trapezoid waves 90° apart. This is done here with IC3A for 270° and 0°. IC3C adds and averages 90° and 0°. You can use other combinations as well. IC3B and IC3D gives the inverse triangle waves. The sines are derived from the triangle with well known “old style” circuitry. The ramp outputs are build from two triangles 180° apart, level shifted and switched between them with the square wave. IC5A takes the 90° triangle, shift it up to 0..10V and lowers the amplitude to 0..5V. IC5B takes the 270° triangle shift it down to 0..-10V and lowers the amplitude to 0..-5V. IC6 (DG409) switches between this two triangles with means of the 270° square. Switching in the right moment put the needed parts of the triangle back together to the saw. The pulse outputs are done with the usual technique moving the switching point of a comparator around with the ramp wave.

PCB quad waveshaper for quadrature thru zero VCO
Triangle screenshot from quad waveshaper for quadrature thru zero VCO
Triangle screenshot from quad waveshaper for quadrature thru zero VCO
Sine screenshot from quad waveshaper for auadrature thru zero VCO
Sine screenshot from quad waveshaper for auadrature thru zero VCO
Saw screenshot from quad waveshaper for auadrature thru zero VCO
Saw screenshot from quad waveshaper for auadrature thru zero VCO
Pulse screenshot from quad waveshaper for auadrature thru zero VCO
Pulse screenshot from quad waveshaper for auadrature thru zero VCO
Quad waveshaper for auadrature thru zero VCO back view
Quad waveshaper for auadrature thru zero VCO back view

NGF Project: Dual Sample and Hold

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Dual Sample and Hold: front view

Dual Sample and Hold: front view

Storing analog signals is a often used function in analog synthesizers. This sample and hold implementation follows closely the original Elektor Formant version of Book 2 “Formant Erweiterungen” p84ff. It is build for my Next Generation Formant project. Because I use the LM13700 here as replacement for the CA3080 I have build a dual sample and hold version. The PCB size is reduced from 100x160mm for a single version to 50x70mm for the dual version.

Specs and features
• Dual sample and hold
• 10Vpp input and output
• Runs on +/-15V and +/-12V
• Power consumption below 25mA each rail

The documentation for download can be found in my website.

Dual Sample and Hold: schematic

Dual Sample and Hold: schematic

This implementation follows closely the original Elektor Formant implementation. Refer to the original documentation if needed. You can find it on the net. My changes are the input buffers, using the LM13700 instead of the CA3080 and the adaption to my 10Vpp signal level.

Dual Sample and Hold: populated PCB

Dual Sample and Hold: populated PCB

Dual Sample and Hold: back view

Dual Sample and Hold: back view

NGF-Project: Elektor Wave Processor

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NGF Project: Elektor Wave Processor

NGF Project: Elektor Wave Processor

A small but very versatile module. It is derived from the original Elektor Formant book “Formant Erweiterungen” p87 ff. Some resistor values are changed to handle the 10Vpp signal level of my system. You can shape the input signal in many ways. You can clip the signal. You can fold the signal. You can emphasize the third harmonic. You can unsymmetrical emphasize the clipped and unclipped signal. You can reverse the input signal. The clipping level is voltage controlled.

Specs and features

• Clipping the signal
• Folding the signal
• Emphasize the third harmonic
• Unsymmetrical emphasize the clipped and unclipped signal
• Clipping level voltage controlled
• 10Vpp input and output
• Runs on +/-15V and +/-12V

The documentation for download can be found in my website.

NGF Project: Elektor Wave Processor, schematic

NGF Project: Elektor Wave Processor, schematic

This implementation follows closely the original Elektor Formant implementation. Refer to the original documentation if needed. You can find it on the net. My changes are the adaption to my 10Vpp system signal level.

NGF Project: Elektor Wave Processor, populated PCB

NGF Project: Elektor Wave Processor, populated PCB

NGF Project: Elektor Wave Processor, rear view

NGF Project: Elektor Wave Processor, rear view

Divide and add

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Divide and add front

Divide and add front

An interesting module to add more color to your sounds. The input signal triggers the 4024 binary counter whenever the signal crosses zero. Therefore you can use nearly any input signal not only squares. The outputs of the 4024 is are added together in two ways. One weighted the other with equal values. The weighted output gives you a more triangle shaped output. You can add lots of harmonics in widely adjustable different combinations.

Specs and features
• Divides nearly any signal
• Weighted and unweighted added output signal
• Add widely adjustable harmonics to you signal
• Runs on +/-15V and +/-12V

The documentation for download can be found in my website.

Divide and add: schematic

Divide and add: schematic

On every zero crossing the input signal triggers the binary counter 4024. The outputs of the counter are adjustable added together weighted and unweighted and the two signals are brought out.

Divide and add: populated PCB

Divide and add: populated PCB

Divide and add: back view

Divide and add: back view

NGF Project: Dual Ringmodulator

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NGF Project: Dual Ringmodulator front view

NGF Project: Dual Ringmodulator front view

I was a bit hesitant doing this module because it uses the now obsolete LM1496 balanced modulator-demodulator. But you can still source them and I have some in my stock. So I decided to make a PCB and module for my Next Generation Formant project. I started with the original Elektor Formant schematic published in “Formant Erweiterungen” p35ff. I left out the microphone and envelope follower part because I already have such modules. I have added input buffers and raised the signal level to my 10Vpp used throughout my system. I was able to put two ringmodulator on a 50x100mm PCB.

Specs and features
• Dual ringmodulator
• 10Vpp input and output
• Runs on +/-15V and +/-12V

The documentation for download can be found in my website.

NGF Project: Dual Ringmodulator schematic

NGF Project: Dual Ringmodulator schematic

This implementation follows closely the original Elektor Formant implementation. Refer to the original documentation if needed. You can find it on the net. My changes are the input buffers and the adaption to my 10Vpp signal level.

NGF Project: Dual Ringmodulator populated PCB

NGF Project: Dual Ringmodulator populated PCB

NGF Project: Dual Ringmodulator back view

NGF Project: Dual Ringmodulator back view

Modulation Sequencer

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Modulation Sequencer populated PCB

Modulation Sequencer populated PCB

This is a small easy to use and easy to build sequencer. The sequence is adjustable from 2 to 8 steps. The output range is switchable from 0..1V to 0..5V. So you can cover 1 or 5 octaves. The sequencer is clocked from an external source. The clock range goes from very slow (LFO) to way above the audio range. When used in the audio range you can realize quite interesting envelope patterns. With the reset input you can start and reset the sequence. This is useful for creating a gated repeating pattern. Many more applications are possible.

Specs and features
2..8 steps
Switchable output 0..1V, 0..5V
Clock input
Reset input
Positive and negative output
Runs on +/-15V and +/-12V (with minor changes)
Power consumption below 10mA each rail

The documentation for download can be found in my website.

Modulation Sequencer schematic

Modulation Sequencer schematic

The sequencer is build around the decimal counter 4017. The clock and reset input needs at least 1/2 off the positive supply voltage to trigger. Therefore the inputs are amplified (IC5C, IC5D, IC1) so you can run the sequencer with lower input voltages. The input circuitry also protects against negative input voltages which are not allowed for the 4017. With the rotary switch you can select the length of the sequence. The rotary switch selects the output which is feed to the reset input of the 4017. The outputs are buffered with the transistors Q1 ..Q8. The emitters are connected to potentiometers which adjust the output voltage. The transistors are driving the LED for the step display as well. The output is buffered with the operational amplifier IC5B. IC5A provides the negative output.

Modulation Sequencer back view

Modulation Sequencer back view

Modulation Sequencer front

Modulation Sequencer front