t_xen Posted January 31, 2008 Report Share Posted January 31, 2008 This idea started because I have an analog synth and a MBSID that I wanted to control with external filters.I created a homebrew AOUT PCB and got a pair of MAX525s as free samples. since I have no drill I surface mounted all the components.I've conceived an idea of the MBHP-AOUT module as a self contained Aout or Aout_NG with it's own dedicated Bipolar Power supply.I constructed the Power supply and populated the DIY Aout board.This Aout is still in the testing phase.The module will include it's own DIN connection (NOT MIDI) for connecting to another DIN wired to the appropriate jacks on the core of a specific midibox project. This will ensure that it's swappable between different Midibox projects. just wire up a DIN appropriate for the added Aout module.Here is a concept design for the panel with the DIN Link.This could be awhile, but I will post pics when all 3 of my projects are in new cases with new panels. ;D Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 1, 2008 Author Report Share Posted February 1, 2008 ok. first test didn't go well at all. I plugged it into my MBCV box and hit the power. got the green LED light. connected my volt meter to the end of the patch cable off the jack and got a steady 10.75v. set the calibration menu to 1v and was still reading 10.7v. I selected 2v and still was reading the same from the patch cable. this reading was taken on CV1. attempted adjusting the trimmer and there was no change in voltage (probably shorted by solder overflow).I hit one of the keys on the keyboard and none of the Gate LEDs lit. for no reason, voltage off the negative rail has dropped to about 1v. I suspect I have a short someplace. likely on the PSU since that's where I checked the voltage.the positive rail is still fine though.so, I wonder if there is a problem with the DIN cable length since I got no Gate indication, but the DACs are getting proper voltage at the correct pins.looks like I have quite a few bugs to work out and fix.I did a trace continuity check on all the pins of the ICs and that came out fine.to do:1. go over board and make sure there are no shorts.2. what IS the maximum length of the DIN cable before the signal across the lines degrade?3. check underside of trimmers to make sure there are no bridges.4. check PSU for shorts and/or breaks. Quote Link to comment Share on other sites More sharing options...
dj3nk Posted February 1, 2008 Report Share Posted February 1, 2008 Do you have soldered the parts on the wrong side ??? Quote Link to comment Share on other sites More sharing options...
Screaming_Rabbit Posted February 1, 2008 Report Share Posted February 1, 2008 Do you have soldered the parts on the wrong side ???Read!since I have no drill I surface mounted all the components ;) Quote Link to comment Share on other sites More sharing options...
dj3nk Posted February 1, 2008 Report Share Posted February 1, 2008 ah, lol sry Quote Link to comment Share on other sites More sharing options...
nebula Posted February 1, 2008 Report Share Posted February 1, 2008 Here is a concept design for the panel with the DIN Link.I don't trust myself to do intelligent things all the time, nor do I trust people who work with me in my studio. For this reason I would consider using a DIN connector with more pins, or D-Sub, or the alternate 5-pin DIN layout, rather than the same connector that we use everywhere for MIDI.Of course that's just me.Also: what kind of transistors are you using for the gates? Are you sure you observed the correct pinout? The negative voltage rail on the AOUT should not have any effect on the gates. Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 1, 2008 Author Report Share Posted February 1, 2008 The trannys I used for the gates are 2 Fairchild BC547A.yes, I payed attention the pinout. ;) Quote Link to comment Share on other sites More sharing options...
xarolium Posted February 1, 2008 Report Share Posted February 1, 2008 I ve just a question t_xen i would like to know with which software do you design your panel.and how did connect the +12v -12v on your Aout Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 1, 2008 Author Report Share Posted February 1, 2008 I used used the Front panel Express (used the print option and save the image as a file) and hand made the images of the connectors, LEDs, screws, ink fill on text engravings on the fly in photoshop.for connecting it to the power, well, because I got the components so close together, I can't get a wire soldered to the 12v +/- points on the board so I had to improvise. I soldered lead wires to the power lines coming from the PSU, and inserted them into the pin sockets (positive into pin 4 in both IC3 and 4 and negative into pin 11 in both IC3 and IC4).I know, sounds like a crack job, huh? :P Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 1, 2008 Author Report Share Posted February 1, 2008 confirmed. issue with the Gates are the result of the overall DIN cable length being a problem. I took a measurement, and the cable is 7 feet causing the signal to degrade before hitting the Aout. Solution, shorten cable, or install buffers as suggested by Bugfight. Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 2, 2008 Author Report Share Posted February 2, 2008 Ok. 2 options: 1. make the serial bus cable shorter 2. implement some sort of line driver.gonna go with the line driver.2 more options: 1. use rs422, or rs232. (overkill) 2. 74HC14 - CMOS Hex Schmitt-Triggered Inverters (for signal boosting)gonna try number 2 first. (Suggested by SmashTV)I'll need to implement this on the serial bus being used to drive the aout across a length of cable.now for the question:do the 3 data lines that run from the core connect to their own single input pin on the 74HC14, and the output pins connected to the aout, directly with no extra components? Here's an interconnection diagram of the 74HC14 placed between the core and aout on the 3 data lines:*(voltage input and ground line connection to the IC left out of this diagram)The 74HC14 will be placed next to the core since the signal will need to be boosted from there.is this all I really need to do or are some filtercaps gonna need to be added (in case of signal reflection)?It can't be that simple. ;p Quote Link to comment Share on other sites More sharing options...
bugfight Posted February 2, 2008 Report Share Posted February 2, 2008 It remains to be seen if this will extend your max cable length, but it is worth trying.Note that you will need to send each signal through 2 inverters in series, though... Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 2, 2008 Author Report Share Posted February 2, 2008 cool. I'll keep that in mind when I try it.It will be about a week until I can test this.Thanks for the tip! :D Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 13, 2008 Author Report Share Posted February 13, 2008 Thanks to Moogah for donating a couple of IC's to this project, I'm going to attempt to try this this weekend. :) Quote Link to comment Share on other sites More sharing options...
bugfight Posted February 13, 2008 Report Share Posted February 13, 2008 we had a conversation in the chat about termination that is relevant here.there's a thread in the german section http://www.midibox.org/forum/index.php/topic,10223.30.htmlwhich shows the effect of termination on a long line. it seems Seppoman has found that AC termination worked very well with 100 Ohm resistor and 100 pF capacitor in series to GND on SC and RC at the last dout registernote that these values may need to be adjusted for particular cable lengths, etc. Quote Link to comment Share on other sites More sharing options...
t_xen Posted February 18, 2008 Author Report Share Posted February 18, 2008 well, crap.haven't gotten to work on this more as of yet.Been busy with hunting down storage, moving, getting every organized ahead of time, work, and blech!I can say though, that this project will placed on hold for prolly about a month after we move and get settled in.I have a front panel on the way for my MBSIDx4v1.Once this arrives, I'll definately post some pics of it in the SID forum as I build Step C, the control surface. :) Quote Link to comment Share on other sites More sharing options...
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