Some notes to build a simple sequencer for the AE modular.
I started building a GATE sequencer then turned it into a melodic one.
This is my 3rd AE modular project ... the first was a LPG followed by a series of clock sources and LFOs
You can of course vary the circuit design to suit Euro, Serge, Buchla etc.
I think the AE modular is a great prototyping platform. It's the main reason I bought one.
The voltages are low & safe.... and breadboards use the same connection cables.
You can literally build your circuit on a breadboard and connect it directly to a modular and see how it works.
This project uses the CMOS CD4017 chip.
It's a 10 step counter.
The AE modular uses +5V so it's perfect
The 4017 has 10 outputs that go high everytime the clock input receives a gate/trigger.
Use something like a pulse from a LFO.
The outs are labelled 0 to 9
12 = carry out
this “carries out” the clock input to an additional counter
13 = clock enable
When it is “0” logic, the clock will get enabled, and the
counter advances one count for each clock pulse. But when “1” logic,
the clock input is stopped, and the counter will do nothing even
when a clock pulse arrives.
14 = clock in
15= clock reset
Normally, it is “0” logic.
When made “1” logic, the counter is reset to “0”.
16 = power (+3V to +15V
8 = gnd
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Pins 13 and 15 must be connected.
They can't be left floating.
Connect these to ground (with pull down 100k resistors).
Parts
+ CD4017
+ 100k resistor x 2 - for pins 13 & 15
+1N4148 diode to protect the clock input and allow only +ve voltages to pass into the chip.
+ use between 1K & 10K resistors to protect the LEDs from burning out.
+ 100k pots x 5 ... depends on the number of steps your sequencer will have.
I started with 4 steps. I'm building a 5 step now
+ SP3T (single pole, three throw) .... adding a switch to change the step length.
+ TL072 or MCP602 (op amps)
+ 1N4148 diodes x 5 (pot outputs)
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I built the sequencer on the same board that I was using for the 6 LFOs
The LFO on the right is the clock source.
Its plugged into Pin 14 of the 4017.
Pins 13 and 15 must be connected.
They can't be left floating. This is very impt !!!!
Connect these to ground (with pull down 100k resistors).
I had to choose how to drive the LEDs.
The 4017 can drive the LEDs on it's own ... does work, but it's a drain on the chip which
may lead to it burning out in the future.
A transistor is preferable since there is less load on the IC.
The trannie is a electronic switch
I used a 1k resistor and a NPN trannie ... 2n3094
Initially I just connected the outputs of the pots (pin 2) to a mult and then connected this to the VCOs CV input.
Seemed to work OK but its actually a bit shoddy as current can flow back into the pot and interfere with the other outs. The fix is of course to add some diodes.
One final thing, .... buffer the output with an op-amp
Common op amps like the TL074, which I initially used require a dual power supply which after I installed the 074, I remembered the AE modular doesn't have.
I'll experiment with LMV358 (dual), LMV324 (quad) and MCP6002,MPC602 & MCP6004 op amps.
These are called rail-to-rail opamps, meaning they work close to the supply voltages.
The only difference is the allowable input and output voltage ranges. "Single-supply" opamps are opamps where the ranges are convenient for use in a single-supply configuration (such as with the AE modular). And yes, of course, you can use a dual supply with a single-supply op amp.
A TL072 may also be Ok for this project.
I used one on my initial breadboard and it seemed to work
In the end I used a MCP602
Supply:2.7V to 6V
I connected Vdd to +5V, and Vss to Gnd
Here is the schemo
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Alternatives of 4017 are as follows:
IC-4060 — 14-Stage Ripple-Carry Counters/Dividers with Oscillators
IC-4020 — Binary Ripple Counter/Dividers, 14-Stage with oscillators
IC-4040 — 12-Stage Ripple-Carry Counters/Dividers
IC-4022 — Divide by 8 Counter IC
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to be continued....................
I may add a clock divider to this board, or a gate sequencer ??
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