Anadums
I’ve been thinking about it a while now, I want to build an analog drum computer.
I’m not trying to emulate legends like the famous 808 or other more current drum computers like the MFB Tanzbär (which btw. sounds wicked, but I can’t afford kit like that, I’m on a hobby budget) or the AIRA TR-8 (which is a really good modernized version of the 808/909, even if it is only virtually analog), but my goals with this project are a bit from the beaten path of arduino drum machines:
the sound creation should be analog. No digital scratching a la what you’re used to hear from Arduinos, and nothing like the teenage engineering PO12 either. Oh, and there are so-called analog drum packs for DAWs around, those are not analog by definition (you dolts! :P). I don’t even want to use a PIC or a digital chip for the noise generator, just a diode or a (half) transistor (you analog electronics afficionados know what I mean) it should be inexpensive, therefore the arduino. Others, like the LDB (the Little Drummer Boy, another DIY project) use PICs and STM32s. I’d like to avoid that (but I do have that micro-STM32 experimental board, so if all fails…) I’ll try and do it with the normal arduino development environment, but will happily switch to plain C if needed. But using the original arduino software means you can have a drum machine, too, even if you’re not into bare-metal programming. the basics: 16 steps, maybe a “funk” button to delay some of the steps, one pot to steer speed, maybe a tapping speed interface (but no pads, the analog inputs of the AT328P seem a bit too simple for that - but hey, there’s a project for you :) ). Output to “normal” 6.35mm jack, mixing is done inside (remember, this is a budget project, I don’t think any users in the hobby sector use to have 24 channel mixers lying around). I might consider it to have a jack per voice, but that depends on me getting a really cheap mixer with at least 8 channels. So, if you are reading this and by any chance are located in Norway, or even better, Tromsø and have an 8+ channel mixer for <500NOK I’d be really really interested. No effects needed, no motorized faders, nothing digital, simple analog mixing will do. MIDI is on the maybe list. I’m undecided, since it complicates the design a bit, and I like it simple. First step: all drum computers have some sort of display for the 16 steps. Since the output pins on an arduino are limited, I did a small experiment with the very nice and very cheap 74HC595 multiplexer chip. For starters I discovered I don’t have enough breadboard wiring for all the LEDs, so some didn’t light up, and I seem to have the sequence a bit weirded up since it did the “groups” right, but in the wrong sequence (from right to left instead of left to right). But anyway, this is what it looked like:
I’m not totally sure I want to use blue and orange LEDs. I could go for the classic red (boring), a combination of red and orange, or I could totally freak out and use blue and white. But I think that at least in a stage environment blue and white would stand out a bit too much and even blind the user.
The thought behind this experiment is also that I have to trigger the analog sounds by some means, as eg. an electrical pulse. Although the pulse for these LEDs probably will be too long, a similar arrangement with those multiplexers could work.
On the other hand I contemplate if I want to add a 1602 display for the programming interface. They’re cheap, they’re fancy and there’s a library for Arduino. But as said above, not everything is futile experimentation :)