16 Step Sequencer (With improved PCB) (+/-9V to +/-15V)
Features
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IntroductionPlease 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
16 Step Sequencer Analog Board Information
16 Step Sequencer (With improved PCB) Analog Board Schematic PDF
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
Parts Layouts (click image for PDF):
Panel Overlays (click image for PDF):
PCB Images X2 Artwork GIF filesBy 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.
Miscellaneous
Adding More Analog Sequencer PCBs"Daisy Chaining" more Analog PCBsYou 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.
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