Unusual Synthesizer Circuits

    I built original modular synths when I was a high school student.  Recently I joined synth-diy
mailing list and resumed synth DIY.  I'm not good at English but I am trying to write most of
the contents in English for the list members who have inspired me.

[WARNING]
   
This page is not for beginners, but for those who are looking for new synth circuits.  Most
of the circuits presented here are not the usual synth circuits.  Beginners must become
familiar with ordinary circuits before they can understand these unusual circuits.  I will not
answer questions from beginners because my English is not sufficiently good to explain these
complicated things to beginners.

    The information provided on this website is for non-commercial use only. Some works
may be covered under one or more patents. Contact Osamu Hoshuyama for information
on commercial use.



Original Schematics

·         Exponential Converter

o    SymExp2.gif (Jan. 21, 2001)     Symmetrical exponential current sources (17 Kb)      Not tested.  But, It should work.

o    ExpPara.gif (May 31, 2005)     Wide-range exponential current source (13 Kb)      Not tested.

o    ExpPent.gif (May 31, 2005)     Multiple exponential current sources (14 Kb)      Not tested.  But, It should work.

o    Exponential converter using MC1496. (Jun. 19, 2008)

o    Single supply exponential converters. (Jul. 01, 2009)

o    Temperature compensated exponential converter using SSM2164 Part 2. (Aug. 29, 2009)

  Temperature compensated exponential converter using SSM2164 Part 1. (Aug. 26, 2009)

o    Temperature compensated exponential converter using Blackmer Cell. (Sep. 02, 2009)

o    Temperature compensated exponential converter using ordinary transistor array. (Sep. 02, 2009)

o    Temperature compensated exponential converter using emitter common transistor array. Easily oscillates. Phase compensation needed. (Nov. 21, 2010)

o    Temperature compensated exponential current source using PNP transistor array. Easily oscillates. Phase compensation needed. (Jul. 14, 2011)

o    Temperature compensated exponential/log amplifiers based on AD538. (Sep. 09, 2011)

·         VCO & Waveshaper

o    VcoMos0212.GIF (Feb. 01, 2003)  CMOS VCO (29 Kb)

o    WvShp0305a.gif (Jun. 10, 2003)   Variable slope-ratio triangular waveshaper (26 Kb)   Untested but tested on simulater by Masa KUNII.  

o    WvShp0306.gif (Jun. 10, 2003)     Voltage-controlled slope-ratio triangular waveshaper (40 Kb)   Untested.  

o    Lfo0509d.gif (Mar. 12, 2006)     Single-OTA VCLFO (10 Kb)      Not tested.

o    RossPhLfo0510.gif (Mar. 12, 2006)     Hyper-triangular LFO in Ross phaser (10 Kb)      Not tested.

o    Serge VCO using LM3900s. (Oct. 08, 2007)

o    AN299 VCO with extended frequency range. (Sep. 30, 2008)

o    VCO using LM359 Norton Amp. (Jan. 13, 2011)

o    Single opamp full wave rectifiers. (Jan. 21, 2012)

  Untested ideas Fwr0306.GIF (May 31, 2005)

o    Saw to sin converters. (Feb. 24, 2012)

o    Through-zero sawteeth VCO with 2 reset circuits. (Oct. 06, 2013) New!

·         VCF

o    Vcf0111.gif (Jan. 5, 2002)         My original VCLPF <Single ended diode ladder>  (12 Kb)    No diff amp. Older Version: Vcf98.gif

o    Ph44core.gif (Dec. 5, 2000)      Pearl phaser PH44 APF core (8 Kb)

o    Vcf99081.gif (Dec. 5, 2000)      My original VCLPF <Totem pole VCF> (28 Kb)

  Vcfhow.gif (Dec. 5, 2000) How the totem pole VCF works (11 Kb)

o    Vcf0007.gif (Dec. 5, 2000)       VCF core variations (HPF and APF) based on the totem pole structure (18 Kb)    Tested on breadboard.

o    Vcf84a.gif (Dec. 5, 2000)         Roland style VCLPF built in 1984. <Normal OTA based>  (18 Kb)

o    PhTrR2.gif (Dec. 5, 2000)        VCAPF <C-E resistor>  (7 Kb)   Tested on breadboard.  Too much distortion.

o    VcfMos0206.GIF (Jul. 25, 2002)   My original VCF <CMOS VCF> (35 Kb)

  CmosOta.GIF  (Jul. 25, 2002) How CMOS inverter works as OTA (18 Kb)

o    PhaseFet0205.GIF (Jul. 25, 2002)   VCAPF idea suited to Mike Irwin's VCR structure (15 Kb) Untested.

o    VcfSvf0206.GIF (Nov. 09, 2002)    State variable type VCF using CMOS.  (20 Kb)

o    Vcf0210.GIF (Nov. 09, 2002)      My original VCF structures using current-input-current-output OTAs.  (19 Kb)

o    Vcf0211a.GIF (Nov. 09, 2002)     Four-pole VCF with asymmetrical distortion. An attempt to simulate SSM2040 for cheap.  (20 Kb)

o    Vcfv0212.GIF (Dec. 31, 2002)     How to add HPF input to ladder filter. Sallen-Key ladder filter is possible!  (19 Kb)

o    VcfTp0211.gif (Jun. 10, 2003)     Totem pole VCF. (26 Kb) A little easy to build. Tested on breadboard.   

o    VcSvf01a.gif (Jun. 10, 2003)     My original multimode VCF. (20 Kb)    Function is similar to Steiner VCF. Untested.

o    Vchp0302.GIF (Jun. 10, 2003)     Horizontal transistor ladder VCF (30 Kb)

o    VcfCtp0211.gif (Jun. 10, 2003)     My original VCF <Cascaded totem pole VCF> (32 Kb) Tested on breadboard.  

o    VcfStn0505b.gif (Mar. 12, 2006)     Modified Steiner style VCF.  (20 Kb) 

o    Svf4023.GIF (Mar. 12, 2006)     Transformation from ordinary state-variable filter to Arp4023.  (18 Kb)

o    VcfSSM0602a.GIF (Mar. 12, 2006)     Four-pole VCF using SSM2164.  (20 Kb)    Main signal path was tested on breadboard.

o    Vcph0505.GIF (Mar. 12, 2006)     My original VCAPF using SSM2164 for phasers. (18 Kb)  Tested on breadboard.

o    Buchla 191 VCF. (Jul. 11, 2007)

o    OSCar VCF & VCA. (Mar. 07, 2008)

o    Battery operated VCF. (Dec. 06, 2009)

  Battery operated VCF Pt.2. (Dec. 06, 2009)

o    Battery operated transistor ladder VCF. (Oct. 06, 2010)

o    Battery operated totem-pole VCF. (Oct. 14, 2010)

o    Phaser based on LM3900. (Aug. 18, 2011)

o    VCLPF based on LM3900. (Aug. 19, 2011)

o    Battery operated diode ladder VCF. (Dec. 02, 2011)

o    Musonic Sonic-V diode ladder VCF. (Jan. 18, 2012)

o    Musonic Sonic-V style VCF with temperature compensation. (Jan. 20, 2012)

o    Single supply OTA based multimode VCF Pt.1. (Feb. 21, 2012)

  Single supply OTA based multimode VCF Pt.2. (Feb. 22, 2012)

  Single supply OTA based multimode VCF Pt.3. (Feb. 24, 2012)

o    Variations of all-pass filters using OTAs. (May. 25, 2014)  New!

·         VCA

o    Vca84.gif (Dec. 5, 2000)         Normal OTA based.  (12 Kb)   CV part has an error.

o    VcaMos0210.GIF (Oct. 14, 2002)     My original VCA. CMOS VCA  (17 Kb)    

o    Vca0302.gif (Jun. 10, 2003)     Discrete VCA with improved dynamic range (9 Kb) Untested.

o    VCAs using MC1496. (Jun. 18, 2008)

o    Class-B ringmodulator using MC1496. (Oct. 26, 2010)

o    Ring modulator with dead zone and saturation. (Nov. 05, 2010)

o    VCA with selectable CV response. (Dec. 09, 2011)

  Variable-response CV current source Pt.1. (Nov. 04, 2011) 

  Variable-response CV current source Pt.2. A little simpler. (Nov. 05, 2011)

  Variable-response CV current source Pt.3.  Far simpler. (Jan. 15, 2012)

o    VCA/Ringmodulator using MC1496. (Jan. 17, 2012)

o    VCA with selectable CV response Pt.4.  Precision response. (Mar. 10, 2013)   New!

o    Ringmodulator using XR2206. (Aug. 29, 2013) New!

·         EG

o    eg0104a.gif (Jan, 2, 2002)       HADSR using CMOS inverters  (17 Kb)    Older Version: eg0104.gif

o    eg0105.gif (Jan, 2, 2002)        HADSR using single-supply bipoler quad opamp  (18 Kb)  Corrected.

o    EgMos0210a.GIF (Jun. 10, 2003)     ADS using CMOS (17 Kb)       Old version: EgMos0210.GIF

o    Eg0301d.GIF (Jun. 10, 2003)     Very simple AD/AR using CMOS 555 (15 Kb)      Old version: Eg0301c.GIF

o    Trapezoid generator using LM3900. (Jun. 23, 2011) 

o    Single-supply envelope follower/generator. (May. 20, 2012) New!

o    AD/AR envelope generators using CMOS flipflops.  (Jul. 01, 2013) New!

o    ADSR envelope generators using CMOS flipflops.  (Jul. 03, 2013) New!

o    ADSR envelope generators using CMOS CD4053.  (Jul. 06, 2013)  Extremely simple.  New!

·         Modification

o    Monotron Modifications.  (Apr. 2010 May 2010)

  Modification Pt.1. (May 10, 2010)

  Modification Pt.2. (May 19, 2010)

  Modification Pt.3.  (May. 29, 2010)

  Modification Pt.4. (Photo)  (Jun. 03, 2010)

  Ribbon pitch range extension.  (Jun. 10, 2010)

  Transforming LFO to EG.  (Jun. 11, 2010)

  VCO mute.  (Jun. 12, 2010)

  External pitch CV input.  (Aug. 03, 2010)

  Additional VCO.  (Apr. 20, 2011)

  Slow attack VCF envelope.  (Apr. 21, 2011)

  Additional LFO.  (Apr. 23, 2011)

  Noise gate.  (May. 26, 2012) New!

o    Gakken SX-150 Modifications.  (2008)

  Traced Schematic. (Sep. 06, 2008)

  Modification schematic. (Oct. 15, 2008)

  Panel design. (Oct. 18, 2008)

  Short demo. (Nov. 11, 2008)

·         Others

o    NgMos0211.GIF (Feb. 01, 2003)     Noise generator using CMOS (11 Kb)

o    ShMos0212.GIF (Feb. 01, 2003)     Sample and hold using CMOS (12 Kb)

o    EfMos0301.GIF (Feb. 01, 2003)     Amplifier and Envelope follower using CMOS (15 Kb)

o    LfoMos0211.GIF (Feb. 01, 2003)     Dual LFO using CMOS (17 Kb)

o    Glide0301.GIF (Feb. 01, 2003)     Glide, Inverters, and Headphone. Amplifier (12 Kb)   Nothing special. Just for Lunch box modular.

o    attmix0301.GIF (Feb. 01, 2003)     Attenuators/Mixer for Lunch box modular (15 Kb)

o    Hfe doubler for low gain germanium transistors.  (Apr. 26, 2006)

o    Quick method for matching diodes/transistors.  (Nov. 10, 2006)

o    Simple noise generator using TL431 Part 2.  (Dec. 03, 2009)

  Simple noise generator using TL431 Part 1.  (Jan. 21, 2009)

o    16 step analog sequencer using CD4017s.  (Nov. 28, 2009)

  16 step gate sequencer using CD4017s.  (Jun. 20, 2009)

o    Filter bank using graphic equalizer IC Pt.1. (Jan. 26, 2010)

o    Filter bank using graphic equalizer IC Pt.2. (Feb. 01, 2010) 

o    Filter bank using graphic equalizer IC Pt.3. (Mar. 09, 2010)

  Photo of the module. (Apr. 24, 2010)

o    Negative series regulators based on TL431. (Feb. 22, 2011)

o    Multifunction LFO/EG. (Jun. 25, 2011)

  Multifunction LFO/EG Pt.1. (Jun. 07, 2011)   Not recommended.

  Multifunction LFO/EG Pt.3. (Jun. 26, 2011)   Exponential curve.

o    VCLFOs based on OTA with various waveforms. (Sep. 18, 2011)

o    Gate sequencers based on 8-step cascading blocks Pt.1. (May 24, 2012) New!

o    Gate sequencers based on 8-step cascading blocks Pt.2. (May 28, 2012) New!

o    Sinusoidal LFOs (Boss VB-2 and Ibanez PH99). (Nov. 06, 2012) New!

o    Sinusoidal LFO with voltage controlled amplitude. (Nov. 07, 2012) New!

o    Dome filter based on twin-T network. (Nov. 08, 2012) New!

o    Dome filter in JH FS-1a. (Nov. 14, 2012) New!

o    Sinusoidal oscillators with bridged-T filter. (Jul. 13, 2013) New!

o    One-knob tone filters for noise Pt.1: Passive filters. (May 25, 2014) New!

o    One-knob tone filters for noise Pt.2: Baxandall style filters. (May 29, 2014) New!

o    One-knob tone filters for noise Pt.3: Blue-to-red filters. (May 30, 2014) New!

o    Low-power noise generators. (Jun. 02, 2014) New!



Photos of My Modular

·         1982-1985 (Dec. 23, 2000. 74 kb)    VCO x 2, Noise, VCF, VCA x 2, S&H, ADSR x 2, AR, Gate delay, RM, Mixer, and Piecewise linear function.

·         1985-2000 (Dec. 23, 2000. 92 kb)    VCO x 2, VCF x 4, VCA x 2, ADSR x 2, Spring reverb, Parametric EQ, Digital delay, DNR, Noise gate, ...

·         2002-2003 (Feb. 01, 2003. 65 kb)    MOSular (CMOS Modular Synth in Lunch Boxes.)   Midi-CV (Synhouse

  Midijack ), VCO x 2, VCF, VCA x 2, ADS x 2, AD/AR x 1, LFO x 2, Envelope follower, Inverters, and Headphone Amplifier. All the signal paths are CMOS.  Block diagram (41 kb).

·         2010 (2010)    Monodular (Modularized Monotron) Link to analog-synth.jp.

 


 

 

 

Mike Irwin's Works

·           Space for Mike Irwin (May. 2002) He is a mastery of modulation effects.


 

 

 


Scanned Schematics

·         VCF

o    moritaVCF76.gif (Jan. 30, 2001. 32 kb)    Tr ladder VCF. (LP and HP) Designed by Shin'ya MORITA when he was a high school student.

o    moritaVCF77.gif  (Jan. 30, 2001. 31 kb)    Tr ladder VCF designed by Shin'ya MORITA in 1977.

o    moritaVCF783.gif  (Jan. 30, 2001. 29 kb)  Diode bridge type 2 pole VCF designed by Shin'ya MORITA. Untested.

o    moritaVCF785.gif  (Jan. 30, 2001. 48 kb)  Diode bridge type 4 pole VCF designed by Shin'ya MORITA. Untested.

o    moritaVCF786.gif  (Jan. 30, 2001. 23 kb)  Re-invention of Moog-Musonics Sonic-V style VCF by Shin'ya MORITA. Tested on breadboard.

·         EG

o    moritaEG78.gif  (Jan. 30, 2001. 42 kb)     Simple ADSR designed by Shin'ya MORITA. 1978.  Untested.

o    gx1eg.gif  (Jan. 30, 2001. 19 kb)            VC ADSR of Yamaha GX1. Redrawn by Shin'ya MORITA.

·         KB

o    moritaKB.gif  (Jan. 30, 2001. 34 kb)        Dual voice KB designed by Shin'ya MORITA. 1977 or 78.


 

 

 

 

 

Mail to Osamu Hoshuyama

http://vpack.www5b.biglobe.ne.jp/vpack/Count.cgi