DBop II - a simple programmable Drummachine...

fonik

hi all,

thanks to dave kendall i was able to upload the original site of tom g's DBop II drummachine. i did not build it yet (i probably never will, who knows) but here is the info for all who are interested.

i will add some better schematics and the 16-step mod soon...

http://www.modular.fonik.de/files/EFMforum/DBopII/title.html
some links will be dead for this only a copied version of the faded original site...

LukeDI · Joined: Sep 23, 2006 Posts: 50 Location: Boston MA, USA

Seems like a neat project and cute too, to bad I've already got a big list of projects to work on.

goodrevdoc · Posted: Fri Jun 29, 2007 5:47 pm Post subject:

Yeah, i've had this for awhile. It one of my favorite things that ive never built. Spent some time breadboarding the individual drum sounds, they are not bad. It would be worth it to build, IMHO, if it were to be adapted to a 16 or dare i say it, 32 step sequencer. all it would take is some extra DIP switches and some more CMOS. I got into it breifly but got sidetracked...
-justin

23isgood · Posted: Sat Jun 30, 2007 3:26 am Post subject:

Does it sound like an 808? Thats what it says in the docs, but does it really sound like one. Are there any audio samples anywhere?

zipzap · Posted: Sat Jun 30, 2007 4:34 am Post subject:

i like trhe sequencer. Don´t get what the and gates after the 4017 are for, though.
Maybe i´ll build one, but i might not use typical drum sounds. If you already have a nice drumbox with sequencer (i´m just planing one), this thing could be added to add some effect sounds and noise patterns.
And an idea i really like: it could be gated not by it´s own clock, but by the master sequencer.
Use it like an individual sound module with a programmable pattern.
For that i would include a reset after step button, so the patterns can be 2-8 steps long.

Or, even more cool and complicated:
I always use a rather fast master clock that is dividet down to drive my sequencers.
Any devision of that fast clock could be anded with the gate from the main drum sequencer.
then this little unit would play rolls and little bursts, or small pattern fragments - all programmed by the dip switches.

fonik · Posted: Mon Jul 02, 2007 1:25 am Post subject:

just added the 16-step mod:
http://www.modular.fonik.de/Page37.html
(scroll to bottom of site)

widdly · Posted: Tue Jul 03, 2007 1:59 am Post subject:

From the page "the clock also gates the 4081 AND gates making sure the output goes off before turning on again". So it gives you triggers at the length of the clock pulse. If you left them out and had two steps on in a row you would only get one long step out.

zipzap · Posted: Tue Jul 03, 2007 8:21 am Post subject:

i see. Well, thre is a way that is simpler, in my oppinion. I used it with my 4017 sequencer. Just an resistor and a cab to ground on every step. Turns the high signal into a short pulse.

fonik · Posted: Tue Jul 03, 2007 8:48 am Post subject:

zipzap · Posted: Tue Jul 03, 2007 3:06 pm Post subject:

that´s true. Embarassed

I remember why i did this: because of lots of different clock dividers and aswing controll of the clock i didn´t manage to get the anding of clock and 4017 right. Like the gate coming with the next step and stuff like that.
No problem with this design.

widdly · Posted: Tue Jul 03, 2007 7:43 pm Post subject:

I would think that the correct cap value would depend on the clock speed.

You could clock it with the blacet midi sync chip and a divider to have midi synced beats.

http://www.blacet.com/MSdata.html

zipzap · Posted: Wed Jul 04, 2007 1:57 am Post subject:

that´s perfect, of course.
I used rather narrow pulses so there is no problem with high clock speeds. The pulses are used to trigger variable gatelength generators (retrigerable).