Step sequencer
This project is similar to the cam shaft sequencer minus all of the moving parts.
I’m still working on getting all of the circuitry right.
There’s a sample at the bottom of the page that I made using the sequencer to control a casio SK1,an analog bass drum synth and an analog noise synth.
There’s also a casper built echo circuit in there.
Here are some pictures of the first prototype.
The sequencer is made up of four rows of 10 switches.
There are four different sequences that can be programmed using the switches in that row.
The left most column is an on/off switch for each row. The right column switches between “short” and “long” mode for each row. In “short” mode, the sequencer creates one 50% duty cycle pulse per step. In “long” mode the sequencer outputs a 100% duty cycle pulse per step. So it will string two or more pulses next to each other into one long pulse the image below should clarify.
Here is the most current schematic.
Here’s an awesome schematic of a programmable, rhythmic mixer sent in by SUBBS. Click the the image below to see a larger version.
Subbs said:
September 15th, 2009 at 4:01pm #
Here is my most recent build for a 4-channel, mixer sequencer. Meant to be played by 2 to 5 people.
4 audio inputs are turned into patterns and beats by the “conductor.”
http://i31.tinypic.com/15n80sg.png
Anyone have advice or corrections?
If anybody wants the full-size image, feel free to ask.
Much thanks to Pete for inspiration and aid.
casper said:
September 15th, 2009 at 6:30pm #
Thanks for the schematic Subbs. I added the picture to the project description above. Do you have any sound samples?
Sheik said:
January 3rd, 2010 at 4:07pm #
What sort of power supply do you use for this?
I understand its 5 volts but, Amperage rating would be very useful.
casper said:
February 18th, 2010 at 1:26am #
@Sheik:The current draw for this circuit is pretty low. I’m sure the greatest pull comes from the relays. All told I’m pretty sure it under 100mA.
mikebike said:
March 21st, 2010 at 9:27pm #
can you explain the short/long step switch?
its seems like you have a NAND gate or something but i dont understand how that makes it short
casper said:
April 11th, 2010 at 1:07pm #
@mikebike: the output of the 4017 is 100% duty cycle. so that means if you have step one and step two on, they will lead right into each other and you’ll have a step that is 2 cycles long. The output of the 555 timer is a 50% duty cycle. The AND gate combines the outs of the 4017 and the 555. The out of the AND is only high when both the 4017 and the 555 are high. SO it will go high when you set the step switch (from the 4017 out) on and for half a cycle because of the 555 50% duty. Make sense??? It’s kind of confusing but relatively simple as far as logic goes.
Mike C said:
April 20th, 2010 at 7:02am #
Does this schematic actually work? I would imagine there is some propagation delay through the decade counter that will prevent the clock signal from lining up with the pulse from the counter at the AND gates… any comments on this?
casper said:
May 2nd, 2010 at 12:57am #
@MikeC:
Yup, it really works. The propagation delay is a few nanoseconds and the length and pulse width of the steps
is long enough that even if they start a few nanoseconds off it doesn’t matter. In a musical context any delay is completely imperceivable. If the sequencer was running at extremely high frequency it might be an issue.
Gord The Rogue said:
July 16th, 2010 at 8:35am #
Hi! A quick question: where do you connect the sequencer’s output on the Casio SK1 circuit board?
On the ribbon pins that recieve the keyboard events or on the classic bend points? Thanks a lot for this great site!
Gord