vidiotsquad » Sequencer

arduino and midi input

bod — Sun, 22 Feb 2009 12:21:51 +0000

i’ve been using the arduino for midi input and output for a while now, mainly using kuk’s input method, output is easy enough though. midi input had me stumped for a while, but he found adding 100k resistor to the base of the phototransistor of the optoisolator created a stable response which sorted it out.

theres alot you can do with variations of his code, and many people have used the circuit to build midi>cv convertors for analogue synths, but at the moment i’m mostly interested in building a clock source for analouge/digital sequencers so i can run them straight from the output of my HR-16 or tr-505 without the need for a computer based midi sequencer. the basic idea is to receive a midi clock byte and advance the count of a 4 bit binary output from the arduino to advance the steps of a multiplexer ic based sequencer.

midi clocks output 24 pulses per quarter note, so this needs dividing down to get the step response you need. the ever useful and highly inspiring code from littlescale comes in handy here!

more soon.

Squarewave Sequencer

bod — Sat, 02 Aug 2008 10:07:21 +0000

While trying to decide what to do with 10 of these 4052b demultiplexers I bought by mistake, I stumbled upon an interesting method of creating a squarewave step sequencer! Its perfect apart from the fact there are only 4 steps, but the method works, so 8 and 16 step versions should be no problem at all, even if it does involve a shed load of diodes…

The issue with these cmos oscillators is the fact they aren’t voltage controlled in the normal sense, so using the standard Baby10 style 4017 sequencer wasnt really an option, until now! So far I have a tempo control, four individual step pitch controls and a master tune control, all running off of 2 oscillators and a handful of components and IC’s.

I love these cmos IC’s, they are like Lego building blocks for noise!!!

Video to follow when i find the camera…..

Video evidence

bod — Thu, 25 Oct 2007 08:14:39 +0000

Here’s a short video showing a working prototype of the 16 step sequencer, using two 4017 decade counters, and a 4081 AND gate. At the moment its only hooked up to 16 leds, with an oscillator controlling to clock speed.

not very exciting admittedly….

16 Step Gate Sequencer

bod — Mon, 22 Oct 2007 09:59:46 +0000

I’ve been working on a sequencer for synths and circuit bent toys using the 4017 decade counter. These IC’s only count up to 10, but I wanted a 16 step sequencer, so after a lot of head scratching and sleepless nights, i managed to cascade 2 of them to give me the 16 steps.

For some reason the suggested circuit in the datasheet for the 4017 didn’t work the way I think it was supposed to, nor did any of the other circuits i could find. It would seem that a bit of hackery is required to get this circuit working.

more later.