Wednesday, 17 March 2010

Patch Tips#3 - Analogue Digital Logic

How to invert digital signals by analogue means.

Today's patch tip is the result of my frustration with Doepfer's A-160 clock divider and the fact that I don't own an A-166 Logic module.

The problem: the A-160 divides incoming clocks like this:

Which is fine for some applications but not when you want all divisions to start on the same, i.e. first, beat. Hook up a couple of sequencers or try to programme a 'straight' drum pattern with an A-160 and you'll soon see what I mean.

More often than not, I need divisions like this:

... exactly the opposite of what the A-160 pumps out.

An A-166 Logic module, with its two digital inverters, would offer a work-around. As I don't have one, I wondered if I could press one of my other modules into performing similar duties. I found the solution in my Bananalogue/ Serge VCS and Make Noise Maths.

Both offer an 'End Out' gate which goes high on completion of a cycle. Patching a Logical 'high' from the A-160 to their inputs causes the End Out to go 'low', in effect inverting the digital signal. For this to work properly, use the 'input' rather than 'trigger' jack and set both the rise & fall times set to zero. With Maths, use channel 4's EOC, rather than channel 1's EOR.

While I don't have enough modules to invert all the outputs of the A-160, this method at least allows me the option of forcing some to play 'on the one'.


REwire said...

Wouldn't any sortof module used in this fashion still make the "One" beat to happen after the divided trigger gets to it? You'd never have a start hit and the corrected hit unless you could mix both and then stop the first one from repeating again and doubling triggers.


Navs said...

I'm not sure I understand what you mean, dAN. Sure, this method will not be instantaneous, so you might run the risk of some flamming. But, it's probably just as fast as a logic/ digital inverter. Fortunately, we now have the 4MS RCD, so the problem of up & downbeat counting is solved :)