#21

Thanks for the detailed response.

So are you using interrupts at all with the Alps, or just taking a straight ADC (10-bit) reading of the position and that’s it?

And are you using this as just a standalone controller?

I’m thinking of making something that houses 3-4 of these along the curve of my snare, along with a few other controllers I now have hanging around there:

IMG_9471
IMG_9471.jpeg4032×3024 2.81 MB

At first I thought about mounting my arc there, but the arc4 is too big/straight, and my (original) arc2 is a bit too heavy/deep to mount effectively.

I looked at @TheSlowGrowth’s arc clone, hoping to have a slightly smaller footprint faux-arc that I could use this way, but it doesn’t look like it would be easily adaptable to that purpose.

1 Like
#22

You could probably do the clone with a custom curved faceplate and solid mounts for the snare.

#23

Do the underlying pcbs lend themselves to not being a long/straight rectangle?

#24

Each encoder has a large and small PCB, and the USB pcb attaches to one of them - http://johannesneumann.net/uploads/images/Gallery/monome/arc/bottom_on_desk.JPG

#25

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Screen Shot 2019-07-25 at 12.15.54.png1224×531 42.8 KB

This is a quick and dirty of what I was thinking

1 Like
#26

How much sexy do you want here? :grin:

I could make you a custom curved pcb for mounting the encoders and set it up like my 4e project (which speaks Arc)

4 Likes
#27

I’m confused - the alps part linked above is a potentiometer, not an encoder.

Is that link incorrect?

#28

Moly moly!!

:heart_eyes:

Oh man, I remember seeing that a bit ago. I totally forgot about it!

What’s the physical resolution on those encoders like? I imagine given their physical size it’s not the same 1000ticks (or whatever the current arc is), but is it >127?

A curved PCB for this would be pretty slick though. What are the physical dimensions of the thing? Didn’t see on the IG post or the github.

#29

I think they are somewhat standard 24 PPR encoders (24 pulses per rotation). I have an enormous bag of plastic shaft encoders that I don’t really have a part number for, so I use them for testing or various prototyping.

The Bourns ones from the Arc clone mentioned way up in the thread (EM14R0D-R20-L064S) are 64 PPR. (and cost $30 each)

As a reference point - the encoders on Norns (and most synths) are probably the same 24 PPR.

Physical size of one 4e (two are shown in that insta picture) is 155mm x 38mm. Don’t have the hardware really finalized so that’s not on github yet.

For the most part this is simply 4 encoders attached to a pcb attached to a Teensy 3.2, and an i2c OLED display (there’s really no other components). I’d probably need to do some fiddling with the encoder reading libraries for the teensy to make the code work with a higher PPR encoder.

I have an idea for “One Knob To Rule Them All” so I keep meaning to get some fancier encoders.

2 Likes
#30

Hmm, I see.

The size is pretty nice, more or less fits between two lugs of a 14" 8-lug snare (actually goes lug to lug, but just to give a point of reference)

The arc compatibility of the 4e is nice, but it may be better to have finer physical resolution even if it’s in the form a potentiometer (sans LEDs), or something like a full-blown “curved arc”-type thing.

(hmm, I guess the boards inside a real arc are separate like that too…, though I wouldn’t want to gut/rehouse mine)

Is the PPR on the full-sized arc clone the same as a real arc?

#31

Well… if you wanted a custom thing, you could choose whatever resolution part you liked :slight_smile:

No - less. I think the real arc is 100 or 1000 PPR? (did some research on this and then forgot)

#32

According to the old forum: 256ppr

1 Like
#33

newest arcs are 1024

I’m prototyping a diy knob thing using a variant of the endless alpha pots. thinking that a polled ADC will be more than sufficient, and the part cost is super super low.

now to find a few spare hours…

8 Likes
#34

You ever think about rolling your own encoders using custom magnets and some hall effect transducers?

#35

That’s true.

That’s what I vaguely remembered (so the newest arcs have 4x resolution of the OG ones).

Oooh. I’m intrigued!

I’m guessing the resolution will then be based on the ADC, so could be at least 10-bit (if vanilla Teensy) or more if using an external ADC.

LED feedback (arc-ish), or just a “knob thing”?

#36

So are you using interrupts at all with the Alps, or just taking a straight ADC (10-bit) reading of the position and that’s it?

Just reading the analog value.

And are you using this as just a standalone controller?

I’m making a 8-knob Ableton/general purpose macro controller with OLED display

2 Likes
#37

I’m confused - the alps part linked above is a potentiometer, not an encoder.

Yes, a pot. And endless pot.

#38

hey wow… i didn’t know that an “endless potentiometer” was a thing. Gonna have to go do some reading.

1 Like
#39

I think they are sometimes called sin/cos pots or something like that. Apparently, Elektron uses them on their new stuff…

Edit: here’s an example part. Edit, edit: someone already mentioned this earlier in the thread but I didn’t notice

#40

What’s that background track you listening to?