d2k Posted November 8, 2004 Author Report Share Posted November 8, 2004 HeyYe, it looks like its coming from the ring in that sch symbol ::)WRT powering th opamp buffer - will a biased voltage be needed - like +/- 12 or can I get away with just using the +9V from the same psu and tie the -V pin to gnd?thanks! Quote Link to comment Share on other sites More sharing options...
moebius Posted November 8, 2004 Report Share Posted November 8, 2004 For that opamp you'll need bipolar supply.. isn't there any on board? (How are those opamp powered?)Bye, Moebius Quote Link to comment Share on other sites More sharing options...
d2k Posted November 8, 2004 Author Report Share Posted November 8, 2004 from checkin the service manual I just see em powered from the +9 or +5 Quote Link to comment Share on other sites More sharing options...
d2k Posted November 8, 2004 Author Report Share Posted November 8, 2004 okay, added the res buffer ckt (all still workin ;p) but there seems to be no dif to the res 'bite' when adjusting those 100k trimmers...just stays the same... ::) Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 Sounds like voltage measurement time, on "live" circuit.. check how much voltages are after buffer..And Casio turned off you can measure resistor values.. Quote Link to comment Share on other sites More sharing options...
d2k Posted November 9, 2004 Author Report Share Posted November 9, 2004 0 (res min) = 0.65V7 (res max) = 2.334V100k trimmer doesnt effect voltage level...And Casio turned off you can measure resistor values..eh? which resistors? Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 Ra, Rf.. are those measurement after the buffer? Quote Link to comment Share on other sites More sharing options...
d2k Posted November 9, 2004 Author Report Share Posted November 9, 2004 Ra and Rf both 1K as u suggested...measurements made after the buffer yesta Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 Ra + trimmer? Those are in series, yes? Opamp powered, with? Quote Link to comment Share on other sites More sharing options...
d2k Posted November 9, 2004 Author Report Share Posted November 9, 2004 Ra + trimmer? Those are in series, yes? Opamp powered, with?well ye - u saw and said is good on the ckt a few posts bak no? power is +/- 12.... the ckt is workin, otherwise it wudnt create any res when the param is changed... Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 Bloody mess...If Ra+trimmer are about 1,5kOhm and Rf 1kOhm.. and opamp input voltage is 2,2v it should give out around 3,67v.. +/-12v power supplies are ok.. (start with higher trimmer values first..)What the f**k is going on there?! Quote Link to comment Share on other sites More sharing options...
d2k Posted November 9, 2004 Author Report Share Posted November 9, 2004 chek the last ckt picture - u SURE it's okay? ??? ::) Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 chek the last ckt picture - u SURE it's okay? Â ??? ::)Oh course not -mee stuupid! Signal should go straight to +input and that Ra (Ra+trimmer) goes from -input to ground... (and Rf is in feedback path from output to -input of opamp)Head bangin' time... Quote Link to comment Share on other sites More sharing options...
d2k Posted November 9, 2004 Author Report Share Posted November 9, 2004 hehe, ye i worked it out after a longass google mission...:0 - res now screamin'! ;)now on to gettin the aout doin the doo (got a core hooked up and handlin midi i/o already)cheers!!! Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 hehe, ye i worked it out after a longass google mission...:0 - res now screamin'! ;)Nice to hear, man! How much the voltage is then?! ;) And, maybe you could post some sound clips somewhere?Bye, Moebius Quote Link to comment Share on other sites More sharing options...
d2k Posted November 9, 2004 Author Report Share Posted November 9, 2004 voltage was around the 3.3V mark max i think - any higher and the res just freaked out completley ;DWill post some clips once the c/v aout bidness is done :)BTW, as this res now scales up to the +3V mark, I'm assuming I need to make one of the LM's on the aout module do the same - meaning having to use the R_* resistors right...? Or can I just stick the resistorless aout c/v signal before the buffer so the voltage will be scaled up to the 3.3? Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2004 Report Share Posted November 9, 2004 voltage was around the 3.3V mark max i think - any higher and the res just freaked out completley ;DWill post some clips once the c/v aout bidness is done :)BTW, as this res now scales up to the +3V mark, I'm assuming I need to make one of the LM's on the aout module do the same - meaning having to use the R_* resistors right...? Or can I just stick the resistorless aout c/v signal before the buffer so the voltage will be scaled up to the 3.3?Hi ya..Just checkin' local "ebay clone" for Casios ;)Ok - You learned the upper limit of res CV, and that Casio design was lame ;)Don't insert cv before the buffer as it protects uC from extrenal voltages...I think you should replace (all Casio related) AOUT buffer resistor values with those on your working buffer.. it would give you the oppurtunity to scale those as fit..Maybe there is more scale to freq controls as well?Bye, Moebius Quote Link to comment Share on other sites More sharing options...
d2k Posted November 10, 2004 Author Report Share Posted November 10, 2004 Just checkin' local "ebay clone" for Casios eheh coo - just as well it's local cos theyre pretty big old things...i've squeezed the main bits into a C64 (breadbin type) case tho, also got a core in there too...and to come the aout...I think you should replace (all Casio related) AOUT buffer resistor values with those on your working buffer.. it would give you the oppurtunity to scale those as fit..so change the 47K cutoff resistors to another buffer ckt with 220k resistors? or r u sayin use the values i have in the current buffer ckt in the aout ckt? So - R_x/y = 1K, R_p = 100k?cheers Quote Link to comment Share on other sites More sharing options...
moebius Posted November 10, 2004 Report Share Posted November 10, 2004 or r u sayin use the values i have in the current buffer ckt in the aout ckt? So - R_x/y = 1K, R_p = 100k?That's what I meant. ;) Quote Link to comment Share on other sites More sharing options...
d2k Posted November 10, 2004 Author Report Share Posted November 10, 2004 ;Dcut and res now under the hands of mios aout control :)response is great :)BTW, for the aout > res connection I had to wire it direct (no resistors) to the buffer input to get the voltage range the same (0-3.3Vish) - as the 100K trimmers on the aout module didnt alter the voltage out (max was 2.summin) - that okay ye? Quote Link to comment Share on other sites More sharing options...
moebius Posted November 10, 2004 Report Share Posted November 10, 2004 ;Dcut and res now under the hands of mios aout control :)response is great :)GGrrreat Work! ;)BTW, for the aout > that okAs long as it works.. seems like uC doesn't give a phuk about it ;)Bye, Moebius Quote Link to comment Share on other sites More sharing options...
d2k Posted November 10, 2004 Author Report Share Posted November 10, 2004 well thanks for the 'elp! ;Dright, now thinking a(b)out  improving the audio section and adding an external input which could be routed thru the filter...for the external input can I just jack in before the vcf? Would some kind of buffer circuit be needed there again?For the audio outs I was thinking of makin each tone and perc signals a seperate output, with the electronically balanced output stage from the ssl comp clone (http://www.gyraf.dk/gy_pd/ssl/ssl_sch.gif)... niceD Quote Link to comment Share on other sites More sharing options...
moebius Posted November 11, 2004 Report Share Posted November 11, 2004 for the external input can I just jack in before the vcf? Would some kind of buffer circuit be needed there again?Well, external input might need some signal conditioning and at least AC coupling (that cap before vcf input in the schematics). What are the levels going to vcf? Maybe just pot for adjusting level and straight non-inverting buffer..Somehow I think that balanced outs are kind of unnecessary in this piece of equipment ;) But individual outs sounds good..As I was looking for peak to peak voltage level for the vcf input - I happened to realize that sounds are generated by actually mixing 2 dac outputs.. Instant new waveforms ;) Just look at page 17 of the datasheet..Bye, Moebius Quote Link to comment Share on other sites More sharing options...
d2k Posted November 11, 2004 Author Report Share Posted November 11, 2004 HeyheyAs I was looking for peak to peak voltage level for the vcf input - I happened to realize that sounds are generated by actually mixing 2 dac outputs.. Instant new waveforms  Just look at page 17 of the datasheet..hmmz, so u sayin slap in a couple of pots where the 820R/130K and 820R/10K meet up (like VR6/9 in schem)...for more (midi controllable) manglin potential ye? 10K d'ya rek to start with?cheers!O ye, i counted 32 options for the data menu pot - do u think a 32 step digital pot would suit spot on, or would a higher 256 step offer greater range for ?snapping? to a specific menu param? Quote Link to comment Share on other sites More sharing options...
moebius Posted November 11, 2004 Report Share Posted November 11, 2004 More like individual pots in place of 820R and 130K / 820R and 10K, or something.. "Lower dac" output looks pretty square (-ish) to me.. Mixin' Â is done in 1:158 ratio, so it's very small component of the sound. With individual controls, you could make new "buzzy" sounds, but probably loose the originals (if you don't make a bypass switch :).. (How do you dial accurately 1/158th or something from a pot? ;)))No midi control here, if you don't cook up some VCAs... O ye, i counted 32 options for the data menu pot - do u think a 32 step digital pot would suit spot on, or would a higher 256 step offer greater range for ?snapping? to a specific menu param? Probably linearity of a digipot is much better than pot onboard.. But does that guarantee snappin'? Who knows ;) You can always hope.. BUT it's better to grap something (at least nearly) MIOS compatible ;)Bye, Moebius Quote Link to comment Share on other sites More sharing options...
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