Jump to content

MB808 from the begining, sources of info

Recommended Posts

It's a simple DOUT based DAC, the ASCII based schematic can be found in the setup_* files (e.g. http://svnmios.midibox.org/filedetails.php?repname=svn.mios&path=%2Ftrunk%2Fapps%2Fsequencers%2Fmidibox_808%2Fsetup_seq_dr_default.asm )


;; CV values can also be output via DOUT shift registers
;; This option is sufficient to control the "velocity" of drum instruments, and it's cheap as well!
;; We expect following connections:
;;   DOUT         160k
;;    D7 ---o---/\/\/\---*
;;               80.6k   |
;;    D6 ---o---/\/\/\---*
;;               40.2k   |
;;    D5 ---o---/\/\/\---*
;;               20.0k   |
;;    D4 ---o---/\/\/\---*
;;               10.0k   |
;;    D3 ---o---/\/\/\---*
;;                5.1k   |
;;    D2 ---o---/\/\/\---*----o CV Out
;;              220 Ohm
;;    D1 ---o---/\/\/\--------o free assignable trigger
;;              220 Ohm
;;    D0 ---o---/\/\/\--------o another free assignable trigger
;; The DOUTx channels are matching with the AOUT channels as specified in the DEFAULT_TRKINFO table above.
;; Allowed values: 1-16 (selects DOUT shift register) or 0 to disable
;; Ensure that DEFAULT_NUMBER_SR is high enough so that all DOUTs are updated.
#define DEFAULT_CV_DOUT_SR1  4
#define DEFAULT_CV_DOUT_SR2  5
#define DEFAULT_CV_DOUT_SR3  6
#define DEFAULT_CV_DOUT_SR4  7
#define DEFAULT_CV_DOUT_SR5  8
#define DEFAULT_CV_DOUT_SR6  9
#define DEFAULT_CV_DOUT_SR7  10
#define DEFAULT_CV_DOUT_SR8  11
#define DEFAULT_CV_DOUT_SR9  12
#define DEFAULT_CV_DOUT_SR10 13
#define DEFAULT_CV_DOUT_SR11 14
#define DEFAULT_CV_DOUT_SR12 15
#define DEFAULT_CV_DOUT_SR13 16
#define DEFAULT_CV_DOUT_SR14 0
#define DEFAULT_CV_DOUT_SR15 0
#define DEFAULT_CV_DOUT_SR16 0


Best Regards, Thorsten.

Link to post
Share on other sites
  • 2 months later...

Thanks Throsten for this!

Dout to CV!


A question for this..

The output voltage is between 0v and +5V right??


If yes is there a way to make this work between 0v and +15?


Or far away better for TR-808: Accent = Trigger pulse between +5v and +15v

My target is to make a Dout Trigger pulse of 1ms width between +5v and +15v ( This will be the accent for 808 voices )



I know i need a shift register that will be operateable at 15 volts..

I found that http://www.ti.com/product/cd4094b can operate at those voltages but this is not a 3-state output register.. Is this a problem?


Regards, Tilemachos

Edited by Navicat
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...