[sdiy] 5v ADV Bass / AD EG Question.
Bill Berzinskas
wberzinskas at nc.rr.com
Fri Mar 18 00:01:15 CET 2005
scratch that.. i had left 1 resistor going to ground still.. 1 more bug to
work out and i think i got it going.. thanks everyone!
----- Original Message -----
From: "Bill Berzinskas" <wberzinskas at nc.rr.com>
To: <jays at aracnet.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, March 17, 2005 5:35 PM
Subject: Re: [sdiy] 5v ADV Bass / AD EG Question.
> would i leave the resistors currently going from + and - to GND?
>
> ----- 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 5:22 PM
> Subject: Re: [sdiy] 5v ADV Bass / AD EG Question.
>
>
> Bill,
>
> I ment that to be the current limiting resistor on the Iabc pin.
>
> What I'd do to get the bias would be take 2 'identical resistors' and put
> those in series between gnd and +5. By identical I would take 1%
> resistors, a good DVM and match them. (Some would take 0.1 decoupling caps
> and parallel the resistors. I don't know how the slew would affect the
> bias.) Now we have a pretty good V++/2. Add another resistor between the
> junction of the two resistors and the plus input on the CA3080.
>
> I've attached a crude jpg of where I'd start.
>
> Jay S
>
> Bill Berzinskas <wberzinskas at nc.rr.com> wrote :
>
>> 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.=
>
>
>
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