Flao's electronics stuffs

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Flao's electronics stuffs

Postby FLAOFEI » 16 Apr 2015 06:54

As some of you may know, I'm now a student of electrical engineering. And as such I have a bunch of classes where I learn certain things, mainly electronics. I have also gained access to an electronics lab with a metric f***-ton of components and equipment for cheap.
What better way to use this newfound knowledge than to build synth gear!?!?! Cause why waste good technology on science and medecine!!! (jk... I'll probably end up doing that later... but for now, time to persue the dream!)

So my first(ish) project will be a 16 step analog sequencer. I've been working a while on the circuit on paper, and tried some of it out on a breadboard. I've got some thinking, testing, decisions and similar work left before I can get to the actual building.

There will be 16 steps with CV-control. They each have a Tune knob, a fine knob, and a little led light showing which step is on. I may add a variable glide function if I can make it work without it affecting, or being affected by the tune knob (also, not adding too manny more components).
I have no plans on adding quantisation or trigger at the moment, since that's probably gonna be a bunch more components.
I haven't designed the actual sequencing part yet, but I plan to use 74-series logic chips. In particular a binary counter controling a MUX which turns on and off the voltage deviders in each step of the sequencer. Since the binary counter is probably gonna be an 8bit counter, I may add in a few switches some logic chips to use the higher bits to modify the pattern, maybe also having a pseudo random switch, to randomise the pattern. As I said, I haven't decided on that yet. It all depends on how few components I can implement things on.

I'll upload some diagrams later.
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Re: Flao's electronics stuffs

Postby Acsii » 20 Apr 2015 07:44

I'm looking forward to it :)
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Re: Flao's electronics stuffs

Postby FLAOFEI » 21 Apr 2015 19:45

So, here are some diagrams!
And explenations!
AND RAMBLING!

Pretty much the layout of the entire thing here
Image
The layout from the bottom up:
Binary counter - That's what counts the steps. It just counts in binary from 0 -> 15 over and over. It's gonna have built in clock as well as being able to take a click track to sync it up with other gear. (just 1 step/click, nothing fancy). I haven't gone into the design of this one in much detail yet though, so I can't say for sure what functionality it'll have, but I'm planing on switching to 8, 4 or 2 steps (maybe any chosen number, if I can figure that out), reverse the pattern, and a pseudo randomizer.
DMux (Demultiplexer) - That's a handy little chip that translates a binary number into a signal on the pin with the corresponding number.
Voltage Dividers x16 - I'll go into more detail on that on the next picture, but the signal from the DMux enables each step, one at a time, in order. Their outputs are allways connected, but they don't affect annything until they are enabled.
And finally, the OP amps - I'll basically use them as a master tune, and to isolate the circuitry from whatever impedance I plug it in to. I'll switch around the amplifier wired OP and the voltage follower wired OP, since as it looks now adjusting resistors in the dividers would affect the amplification of the amplifier.

The voltage divider I plan on building for each step
Image
I've put a lot of thought into this guy
What I've labled as "Chose step in" is connected from the DMux, and into the transistors that power the contraption. That's the enabling I wrote about above.
There are knobs to tune, fine tune, and adjust glide time. It will always glide from V- or from V+ to the level of the CV depending on the setting on the glide switch, either in up, down or off mode. The glide time can be set from instant to ~10s. I might add a short/long switch to the glide function, to get better control over short glide times.
I realise now how I could make it glide from wherever in the range... I doubt I'll do it though, since I'd need yet another pot per step.

If you have any questions on how stuff works I'll be happy to answer. And if you have opinions on what I should do with the sequencer, or just an opinion about how to run this thread efficiently, just let me know.
There's also a tiny littl led indicaring the step is active. Did I mention it's orange?
)>-<)))^*> Sharkpon4srs
https://soundcloud.com/flaofei/brothel-king
Rainbow Dash lives on SOUNDCLOUD; Big Mac posts on Eeyyuptube; Twilight is a BOOKfACE; Octavia went to BandCamp! And Derpy has bad balance, you could say she TUMBLrING
ImageOMG POLKA PLOT!!! BEST ALBUM IN THE HISTORY OF POLKACORE!!!
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