[sdiy] 5v ADV Bass / AD EG Question.

[Bill Berzinskas]

gnd and 5 indeed..    as far as biasing..   u say 5.1k..   so, this would be 
a voltage divider..   does it go  on my signal input or the pin5?


----- Original Message ----- 
From: <jays at aracnet.com>
To: "Bill Berzinskas" <wberzinskas at nc.rr.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, March 17, 2005 4:25 PM
Subject: Re: [sdiy] 5v ADV Bass / AD EG Question.


> If it is between gnd and +5 then you will probably have to bias the input 
> to ~+2.5 volts. Basically V+/2. You'll have to be careful since the 3080 
> has a fairly low input voltage for low distortion so bias become critical.
>
> Also be careful. If the Iabc pin gets to much current it can fry the 
> CA3080. So at least in prototyping the circuit add a current limiting 
> resistor.
>
> Crude calculation:
> V=IR, R = V/I, V=5, I=.001 (1ma), R=4.7K or 5.1K should work.
>
> Jay S.
>
>
>
> Bill Berzinskas <wberzinskas at nc.rr.com> wrote :
>
>> well.. i breadboarded this this morning..  and
>> most everything seems to work..  except the vca..  any 
>> thing
>> specific i need to do to get this 3080 vca working 
>> on 5v?  
>>
>>  
>>
>>   ----- Original Message ----- 
>>   From:
>>   Bill
>>   Berzinskas
>>   To: Jay Schwichtenberg ; synth-diy at dropmix.xs4all.nl
>>
>>   Sent: Thursday, March 17, 2005 11:16
>>   AM
>>   Subject: Re: [sdiy] 5v ADV Bass / AD EG
>>   Question.
>>
>>   preciate that jay..   good
>>   article..  it'll prob take me a bit to get through the math tho.. 
>> lol
>>   ..  :-)    time to break out my math book from last
>>   semester..
>>    
>>
>>     ----- Original Message ----- 
>>     From:
>>     Jay
>>     Schwichtenberg
>>     To: Bill Berzinskas ; synth-diy at dropmix.xs4all.nl
>>
>>     Sent: Thursday, March 17, 2005 11:10
>>     AM
>>     Subject: RE: [sdiy] 5v ADV Bass / AD EG
>>     Question.
>>
>>     Bill,
>>      
>>     2)
>>      
>>     Another issue is that the attack, decay and release
>>     pots on envelope generators are typically log pots, a non-linear 
>> scale.
>>     So if the digital pots you use are not log they may not give you the 
>> timing
>>     resolution that you are use to. One techinque to do that is buffer 
>> the pot
>>     and add a resistor. Picking the right resistor and placing it between 
>> the
>>     wiper and the other ends of the pot (assuming using pot as attenuator
>>     between signal and gnd) can give you log or expo curves. Try 
>> http://www.geofex.com/Article_Folders/potsecrets/potscret.htm for 
>> that
>>     info.
>>      
>>     Good luck.
>>     Jay S.
>>
>>       -----Original Message-----From:
>>       owner-synth-diy at dropmix.xs4all.nl
>>       [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Bill
>>       BerzinskasSent: Thursday, March 17, 2005 7:36 AMTo:
>>       synth-diy at dropmix.xs4all.nlSubject: [sdiy] 5v ADV Bass / AD EG
>>       Question.
>>       Hello everybody..  just woke up to a
>>       crazy little burst of snow here in NC..  wierd..  
>>
>>        
>>       Anyhow..   As you probably know i'm
>>       modding the bejezzus out of my adv-bass..   In my quest 
>> to make
>>       it digitally controlled, i've hit a few snags..  so maybe you 
>> can
>>       help me out..
>>        
>>       1) I am converting it to digital
>>       control..  mostly thru digital pots..   a few things 
>> with
>>       DAC..  so.. for the digital pots, i have to use 5v input, and 
>> rather
>>       then use way more opamps then i want to deal with, i would like to 
>> make it
>>       operate on 5v possibly with a bipolar or just 12v output stage if
>>       necessary..   So..
>>        
>>       I've done some crude experiments with the
>>       Trigger section just to see how it reacts to switching from +/-12v 
>> to just
>>       +5v..    I've tried with tl082s..  and i just 
>> can't
>>       get the trigger ratio right.. and it always triggers.. so.. since i 
>> broke
>>       down and got a few lm324s, i tried those.. and it seems to be 
>> working
>>       correctly..   i then went on and built the impact part 
>> using the
>>       digital potentiometers..   all good so far..   
>> if i
>>       just switch all my opamps in the design, will it carry through the 
>> rest of
>>       the circuit properly?
>>        
>>       2)  I plan to use a digital
>>       potentiometer to control the decay time..   but the 
>> highest
>>       value i can come up with is 100k.. so i'm thinking i can change the
>>       capacitor and get about the same decay time?   any
>>       recommendations for a value?
>>        
>>       thanks guys!  :-)
>>       --billie
>>        
>
>
>