16 Step Sequencer (With improved PCB) (+/-9V to +/-15V)

Article by Ray Wilson
Back to "Music From Outer Space" Analog Synth Pages

Watch Thomas White's Excellent
Sequencer Videos on YouTube

Thomas White used the MFOS sequencer boards to produce this incredible rotary sequencer. Visit his site to keep up with his latest awesome projects.

Features

  • Improved PC board (far less kludging).
  • Produces sequences of 4 to 16 steps in length
  • Modes include stop at count, reverse at count,
    reset at count and random 16 mode
  • Each step has coarse tune, fine tune, and switchable gate
  • Accepts external clock and external start pulse.
  • Simultaneous outputs with and without portamento.
  • Forward, Back, and Reset controls ease sequence set up.

 

 

Introduction

Please see the pages at 16 Step Analog Sequencer Circuit for details regarding circuit descriptions etc. This page is here soley as a vehicle to present the new PC boards and support board purchases. The schematic and PCBs presented here incorporate all of the improvements and modifications shown on the previous sequencer pages. Panel to board wiring is presented here. Please browse the entire page before ordering board to ensure you understand the circuit and there is enough information provided here for you to successfully complete the project prior to purchasing PC boards. Thanks.

NEW!
  Adding More Analog Sequencer PCBs

This is an advanced project and I do not recommend it as an intermediate or first project if you are just getting started in synths or electronics. Only the circuit and some explanation are shown here. A lot of project building experience and electronics knowledge and equipment ownership (scope, meters, etc.) is taken for granted. If you are interested in building this project please read the entire page before ordering PC boards to ensure that the information provided is thorough enough for you to complete the project successfully.

16 Step Sequencer Digital Board Information


16 Step Sequencer (With improved PCB) Schematic Page 1 PDF


16 Step Sequencer (With improved PCB) Schematic Page 2 PDF


16 Step Sequencer (With improved PCB) Schematic Page 3 PDF


16 Step Sequencer (With improved PCB) Panel Wiring PDF


16 Step Sequencer (With improved PCB) Board to Panel Wiring PDF

16 Step Sequencer (With improved PCB) Digital Board Parts List

Qty. Description Value Designators
3  CD40106(s)  CD40106  U2, U1, U6  
1  CD4013 Dual D Flip Flop B  CD4013-B  U3  
1  CD40193 4 Counter  CD40193  U4  
1  CD4094 8 Stage Shift/Store Reg  CD4094  U8  
1  CD4514 4 Bit Latched 4 Dec.  CD4514  U5  
1  TL082 Dual Op Amp  TL082  U7  
17  LED(s)  General Purpose LED  LED1, LED5, LED3, LED9, LED7, LED13, LED11, LED17, LED15, LED4, LED2, LED8, LED6, LED12, LED10, LED16, LED14  
31  1N914 Sw. Diode(s)  General purpose high speed switching diode  D2, D5, D6, D7, D1, D11, D3, D4, D8, D31, D9, D15, D12, D19, D17, D23, D21, D27, D25, D26, D24, D22, D20, D16, D18, D14, D10, D13, D28, D29, D30  
1  2N3904  2N3904  Q1  
1  Tantalum Capacitor  1uF  C10  
4  Ceramic Capacitor(s)  .001uF  C14, C12, C13, C18  
8  Ceramic Capacitor(s)  .01uF  C22, C23, C1, C3, C8, C7, C15, C16  
5  Ceramic Capacitor  .022uF  C9, C2, C4, C5, C6  
2  Ceramic Capacitor(s)  .1uF  C19, C24  
1  Ceramic Capacitor  100pF  C17  
1  Ceramic Capacitor  47pF  C11  
2  Electrolytic Capacitor(s)  10uF  C20, C21  
1  Linear Potentiometer  1M  R19  
8  Resistor 1/4 Watt 5%(s)  100K  R47, R9, R46, R44, R45, R28, R26, R32  
7  Resistor 1/4 Watt 5%(s)  10K  R1, R5, R10, R11, R17, R20, R39  
4  Resistor 1/4 Watt 5%(s)  1K  R42, R41, R29, R27  
4  Resistor 1/4 Watt 5%(s)  1M  R13, R14, R33, R38  
1  Resistor 1/4 Watt 5%  20K  R18  
4  Resistor 1/4 Watt 5%(s)  220K  R7, R3, R16, R21  
2  Resistor 1/4 Watt 5%(s)  2M  R31, R35  
1  Resistor 1/4 Watt 5%  3.9K  R43  
2  Resistor 1/4 Watt 5%(s)  3K  R24, R30  
3  Resistor 1/4 Watt 5%(s)  4.7K  R25, R37, R34  
1  Resistor 1/4 Watt 5%  4.7M  R36  
4  Resistor 1/4 Watt 5%(s)  47K  R40, R12, R8, R4  
1  Resistor 1/4 Watt 5%  6.2K  R23  
4  Resistor 1/4 Watt 5%(s)  680K  R2, R6, R15, R22  
1  12 Pole Rotary Switch  SP12T  S9  
1  1P4T Selector Switch  SP4T  S25  
1  DPDT Switch  DPDT  S12  
4  SPST PB Switch(s)  SPST  S1, S2, S3, S4  
16  SPDT Switch (used to accomodate the gate diode and LED wiring)  SPDT  S5, S7, S10, S13, S17, S19, S21, S23, S6, S8, S11, S14, S18, S20, S22, S24  

16 Step Sequencer Analog Board Information


16 Step Sequencer (With improved PCB) Analog Board Schematic PDF

Either 2.5 Volt Reference chip will work.


16 Step Sequencer (With improved PCB) Panel Wiring Diagram PDF


16 Step Sequencer (With improved PCB) Gate Switch Wiring Detail PDF


16 Step Sequencer (With improved PCB) Board to Panel Wiring Labels PDF

16 Step Sequencer Analog Board Analog Board Parts List

Qty. Description Value Designators
1  CD4067 Analog Mux/DeMux  CD4067  U2  
1  TL082 Dual Op Amp  TL082  U3  
1  TL084 Quad Op Amp  TL084  U1  
1  LM336 2.5V Ref.  LM336-2.5V  VS1  
32  Linear Potentiometer(s) (don't forget to buy knobs)  100K (up to 500K will work fine.)  R11, R19, R32, R38, R46, R54, R63, R69, R4, R8, R18, R35, R44, R53, R62, R13, R22, R40, R34, R48, R57, R71, R66, R7, R15, R30, R24, R42, R50, R67, R59, R28  
1  Linear Potentiometer  1M  R51  
18  Resistor 1/4 Watt 1%(s)  100K  R10, R31, R45, R17, R36, R12, R33, R47, R65, R6, R41, R58, R5, R52, R23, R64, R26, R73  
3  Resistor 1/4 Watt 1%(s)  10K  R74, R72, R1  
1  Resistor 1/4 Watt 1%  200K  R25  
1  Resistor 1/4 Watt 1%  22 ohms  R75  
16  Resistor 1/4 Watt 1%(s)  2M  R27, R20, R37, R68, R21, R39, R70, R14, R29, R49, R9, R60, R55, R61, R56, R43  
2  Resistor 1/4 Watt 1%(s)  47K  R3, R2  
2  Ceramic Capacitor(s)  0.1uF  C4, C1  
2  Ceramic Capacitor(s)  470pF  C6, C5  
2  Electrolytic Capacitor(s)  100uF  C3, C2  


Parts Layouts (click image for PDF):


Panel Overlays (click image for PDF):


PCB Images X2 Artwork GIF files

By the time you've etched (double sided by the way) and drilled (587 holes) these boards yourself you'll wonder why you didn't buy the professionally manufactured, glass epoxy, plated through-hole, double sided, soldermasked, silk screened legend board from me. But have at it... These X2 images are provided for individual use and not for mass production or sale.

Download ZIP file.

Miscellaneous

  • 1/16" to 1/10" Thick aluminum plates for mounting the pots and switches.
  • Wood or plastic to build a case with.
  • Assorted hardware 1" 6-32 nuts and bolts, 1/2" #8 wood screws, etc
  • Knobs for potentiometers, wire and solder.
  • Digital Volt Meter and a Signal Tracer or oscilloscope for testing.


 

Adding More Analog Sequencer PCBs

"Daisy Chaining" more Analog PCBs

You can drive more than one analog sequencer board from one digital board. This is accomplished by chaining the QA, QB, QC, and QD connections from the digital sequencer board to one or more additional analog sequencer boards. The illustration below shows this. Each additional analog PCB requires it's own set of coarse and fine pots and a new set of CV output jacks and portamento control. These are mounted on a panel and wired just like the original set of coarse/fine pots, CV out jacks and portamento pot.

The result is that you can now control separate modules with a synchronized 16 step sequence. You still only get 16 steps. Adding analog PCBs does not result in more steps. Adding more analog boards lets you do things like: have a 16 step sequence of chords (controlling separate VCOs) or control a VCF with one set of controls and some oscillators with the other set. You can imagine a ton of cool applications.

How should I drive additional channel indicator LEDs?

Although you can probably get away with another set of LEDs being driven in parallel with the original ones I recommend that you isolate the original driving circuit and add buffers of one kind or another to each set of new LEDs. Below I show three different ways to drive an expanded analog section's indicator LEDs. One way uses NPN transistors as buffers another way uses hex inverting Schmitt triggers (CD40106) and finally a single chip solution is to use a CD4514 (CMOS 4-Bit Latch/4-to-16 Line Decoder). Either will work fine and either can be built on a small daughter board. The choice of which to use may be as simple as what's in your parts cabinet currently, trannies, inverters or a spare CD4514.

Here, transistors are used to drive the LEDs. The original S0 through S15 circuit points can be accessed at the digital board by carefully tack soldering the new wires to the bottom of the board or at the panel where they connect to the gate switches and LEDs. A successfully tack soldered joint should look nice and shiny (like any other solder joint). If your tacked connection turns out clumpy then use some fluxed braid to remove the excess and try again.

Here I show you how to use inverting buffers to drive the LEDs. This method uses way less parts and is probably my favorite. Either of these methods should fit nicely on a small daughter board.

Lastly this is the CD4514 method. It uses one chip and notice that the QA thru QD inputs are used to drive it. These come from the analog board and will most likely need to be tack soldered to the bottom the QA thru QD pads on the board.