percussion sequencer?

[choklitlove]

i've been thinking about this, as i'm trying to wrap my head around the entire sequencer thing.

a sequencer takes programmed voltages and loops them, triggering whatever is controlled by those voltages, i.e. notes on a synth. is that close? if not, what exactly does that?

if we had a separate circuit for say, three different types of drum sounds, and each was triggered by a piezo element. a "hit" on a piezo element is a voltage itself, correct? could we set up a sequencer to 8 steps (1 measure, eighth notes), and programmed 8 drum hits into it? so it would loop a 1 measure, 8 eighth note pattern.

i also thought an "empty" step would be handy. like the equivalent of an eighth rest. what about that?

it was just me thinking randomly, and as usual not understanding things. so enlighten me!

[Uncle Krunkus]

Yep, that's exactly right.
A drum machine is basically just a sequencer where the gates can be sent to trigger multiple voices. If your voices are relatively fixed, you only need the gates. This could be built with just a 4017 (or similar). If however you include a method for dialing up a CV for each step (most analogue sequencers) you can use this to vary volume, tone, waveshape, etc. for each step. This can have great results even if you've only got one voice.

[Scott Stites]

Step sequencers work more or less like those marquee lights that you see on movie theaters - the one's where the lights chase around and around.

If you imagine that only one light is going around and around, that's pretty much how a step sequencer works. Each time a light bulb goes on, the voltage assigned to that light bulb is present on the voltage output of sequencer. Also, when that light bulb goes on, a gate is triggered on the gate output. Then that light goes off and the next light comes on. Then, the voltage programmed for that light is present on the voltage output of the sequencer and a gate signal is generated on the gate output of the sequencer.

Like you say, this process loops around and around. The voltage on the voltage output changes with each change of lightbulbs, and each time a new lightbulb goes on, a gate signal is produced from the gate output.

If you have eight lightbulbs, then for each iteration of the loop, you get eight gates. Of course, the gates can easily be triggers instead, but you get the point. But, yes, if you connected this gate output to a drum voice, you would get eight eighth notes per measure.

The ability to create rests depends on the sequencer. Most sequencers will give you this ability one way or another.

Some sequencers have a separate jack per light bulb. When the lightbulb associated with the jack goes on, a gate signal is sent out that jack. If you combine different jacks to a single output, you will be able to get rests. For example, say you combine jack 2, jack 4, jack 6 and jack 8 into a common output - now you will have four quarter notes for your eight beat measure.

Of course, you could combine any number of these outputs to get irregular beats, etc.

Now, many sequencers also provide what's known as a bus for distributing these signals. Usually there are two or three busses. Each bus has a common output.

For each lightbulb, there is a switch that will determine if that lightbulb's gate signal is going to be sent out of bus 1's output or bus 2's output, or bus 3's output. So, once you have your switches all set up, some gate signals will go out one bus output, while other gate signals will go out the other bus outputs.

In this way, you can set up a drum voice for each bus output and have all three drum machines playing a different 'beat' in that measure.


Edit: Aahhhh pooo - had a spiffy asterisk based illustration that didn't format right.

Hope this helps,
Scott

[blue hell]

[choklitlove]

okay, sequencers have "pulse outs" for each step, right? how are those programmed? or is it just whatever is connected to each one takes that step? is that where those matrices with all of the jumpers come into play? like, each step has its own jack, then you jumper that to whatever you want triggered for that step. that makes sense to me... am i thinking in the right path?

if what i just said is true, how would i make buttons for each triggerable sound, and just press them in order to program the sequencer?

what i'm thinking is similar to mike's "silver sequencer" thing i was talking about a couple weeks ago, just in case it doesn't make sense.

[Clack]

i think It all depends on the type of sequencer,

yeah so an analog gate sequencer would need a trigger out for each sound you want to trigger , you would need a seperate sequence for each sound.

your basic sequencer has a counter that counts 1 - 2 - 3 - 4 .. looping, then on each of those steps you have a different channels for each sound with a corresponding switch on / off - in a matrix. so if it got to step 4 and the switch is on on channel 1 a snare will sound

+'s are the switches

[Scott Stites]

[MIKEFORD]

Here is something I want to incorporate with about 4 of marc brailles ds7 clones(gotta order some PCBs from him in France this summer!)
here is the link
http://www.sailormouth.org/index2.php?pg=seq.inc
Good Luck

[RF]

I've been building this....
http://www.cgs.synth.net/modules/gate_sequencer2.html

..it could be what you are looking for....

[Photon]

the MM5871 Rhythm Generator IC is still available if you hunt around. There a 4 or so on ebay right now for $8 ea. Delton Horn's book, "Music Synthesizers : a Manual of Construction" has some info and circuits for using this chip.

peter

[Mikmo]

If you don't mind a PC beeing part of the system you should take a look at the simple parallel port interface and trigger sequencer program i made for triggering circuit bend toys. It could be used to trigger anything that a switch could trigger. Limited of course to what the 4066 IC allows.

http://www.mikmo.dk/cbsequencer.html

http://www.mikmo.dk/cbinterfacedetails.html

Only problem is that the sequencer program does currently not synch to any thing else.