[sdiy] CMOS Synth

[Scott Gravenhorst]

harrybissell at prodigy.net wrote:
>Hi Magnus:
>
>My reply was not 'strictly' a comment on the 4069... but 
>was to address the concerns of those who wanted to limit the
>power dissipation of CMOS linear circuits.
>
>Other ways would be to lower the supply voltage to the minimum
>possible...
>
>Using fewer inverters per package would help as well... not on overall
>power consumption, but at least in temperature rise per package.
>
>The "all 4069" might be a fun project but I doubt I'd try it
>anytime soon. (well maybe if I was stranded on a desert island
>with nothing BUT 4069).  There would not be too much benefit from
>cost, performance, etc.

Although I think that Magnus's idea of an all 4069 synth is admirable and fun from the standpoint
of mental gymnastics, I must agree with Harry.  I just don't have the time, and the little time I
do have, I've decided to spend on making things that perform well enough for musical use in a
FatMan environment.  In fact, I could never claim "all 4069 synth" anyway, because I'm spending my
time building up enhancements for my two FatMan synths.  I've built several "modules" of all 4069,
but I must admit, there are things about the 4007 that are just too convenient to ignore.  Probably
the biggest reason for me to do any of this is that CD4xxx and equivalent parts are still readily
available and relatively inexpensive.  If I can make circuits with these parts to function well
enough for music electronics in associate with the FatMan, I do.

BTW, I thought the suggestion of using lower voltage is a good one, especially for an all CMOS or
all 4069 synth.  Preamps and attenuators could be used to allow interface with other synths, but
for my case that would complicate matters.  For example, I have a 4069 dual LFO that would probably
run from the minimum of 3 volts, but then I'd need an opamp to be able to drive the FatMan with it.
 That defeats the purpose of having avoided opamps for the LFO in the first place.

Now, were I to win the lottery, I'd have time (and money) to start from scratch and attempt this
(with the kindly help from this list).  As it is, I've used the FatMan as a synth base that went
together in hours as opposed to months.

None of this is meant to take away from the Magnus "Grand Idea" at all.  I just wish I had more time.

As they say, "Wish in one hand, poop in the other, which one fills up first?"...

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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