Kits: Voice of Saturn Sequencer
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Short Description:
This is a 10 step analog sequencer, which basically steps through 10 different
voltage levels that are set by the black knobs. The output control voltage and trigger
signals are typically used to control pitch, filters, drum triggers and an endless
number of other parameters on other synths.
It's based on a decade counter chip (CD4017) driven by a 555 timer (clock), although it can also use an external clock signal. The sequence can be shortened by connecting an eigth-inch audio cable from the reset jack on top to one of the step's jacks. It features both a gate output and a S-trigger output for Moog synths. Skill level: Intermediate... maybe beginner |
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Post mods / hacks, pics, videos and support questions here. We'll be giving away a limited number of toys to anyone that posts a video or hack.
VOICE OF SATURN SEQUENCER
- The 10 step sequence can be shortened by connecting a 1/8" male-male audio cable from a step jack to the main reset jack.
- The internal clock can be bypassed so that an external clock can drive the VoS Sequencer. We're not entirely sure what types of clocks it's compatible with, however. The internal clock can also be output to drive another device.
- Features both a Gate out and S-Trigger out for older Moogs.
- Battery powered: you may want to add a fixed voltage supply to keep the CV levels from drifting as the battery dies, although we've found it to last a long time.
- When the clock switch is off, the hold switch can be used to manually step through the sequence.
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Bare-bones-kit
in stock
- $69.99
Including just the essentials for installing in your own Ikea bowl or other custom case. Click the picture for a larger version.
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Everything-kit
in stock
- $124.99
Everything you need to make the full kit, including knobs and a pre-drilled and silk-screened case.
Click the picture for a larger version.
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Fully assembled and tested
in stock
- $249.99
Works out of the box, no assembly required.
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- U1: LM555N timer (spec) (buy)
- U2: CD4017 timer (spec) (buy)
- Capacitors:
- (13) spdt toggle switches (buy)
- (15) 1/8" audio jacks (one switching) (buy)
- (11) R17 thru R27: 100k linear potentiometers (buy)
- Resistors:
- Transistor: Q1, 2N3904 (buy)
- (21) Diodes: D1 thru D22 (buy)
- (11) Red LEDS: D22 thru D32 (on panel) (buy)
- (11) Panel Mount LED holders (buy)
- (1) Custom PCB (buy)
- 9V Battery and holder (buy)
- (10) black knobs (buy)
- (1) red knob (buy)
- A silk-screened and pre-drilled case, with hardware and rubber feet (buy unfinished case)
- (6) 4-40 nuts (buy)
- (6) 4-40 screws (buy)
- (4) standoffs for the PCB (buy)
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Detailed assembly instructions are here => Instructions
Click for larger version.
Quick Operation Guide:
The sequencer has two main outputs: the CV (control voltage) and gate output. The gate output can be thought of as the trigger or note-on message, and the CV as the pitch or general purpose control level. The knobs on each step adjust the CV level for that step, and the switches control whether the trigger signal makes it to the gate output.
The S-trigger output is a special gate output for some Moogs.
You can shorten the sequence by connecting an 1/8" audio cable from a step's jack to the reset jack on top.
Important: The sequencer can be driven by an external clock by plugging into the "Clock Out" jack on top. However, you must first turn off the Clock switch to prevent the internal clock from fighting this external signal. If the Clock switch is on, you can tap into the clock signal through the "Clock Out" jack and use it to drive other equipment.
The best way to set each CV level is to turn the clock off, and toggle the hold switch to manually step through the sequence. The hold switch stops the sequence when the clock is on, too.
How the circuit works:
Here's an overview:
The 555 is setup in a "monostable" circuit, and is used to generate a square wave with a rate that's adjustable with a 100k potentiometer. This square wave feeds into the 4017, which turns on each of the 10 steps sequentially with every rising clock edge.
The line from each step output on the 4017 goes to a LED and 1/8" reset jack. When a cable connects one of the step's reset jacks to the main reset jack, this passes the signal to the reset pin on the 4017. This is how the sequence can be shortened.
Each output step on the 4017 also goes to a switch that can then pass along or block the signal to the gate bus and main CV (control voltage) output through a pot. If a switch is off, it prevents that "note" from playing. Diodes are used to prevent a high output on one step from feeding back into a low output on another.
The S-trigger output is just a transistor switch that pulls the line down to ground when a trigger fires.
(complete instructions)