[sdiy] CMOS Synth

[Magnus Danielson]

From: harrybissell at prodigy.net
Subject: Re: Re: [sdiy] CMOS Synth
Date: Mon, 03 Feb 2003 09:11:51 -0800

> Hi Magnus:

Hi Harry,

> 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.

Right.

> 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.

Indeed, and I've never envisioned it to be a very mature result. More like a
little quirky thing on the side for a few blips and blops, like a Paia Gnome or
something. It's certainly not a high-priority project, but I've seen enought
magic being made by 4069s that I think it is feasable to actually get something
kind of working.

> As you correctly observe... the entire exercise would be mental...
> to think "outside the box".  I think that engineering already
> provides the same pleasure of making the choices and trade-offs
> involved in making a good design.  It might be more fun to try and
> meet some other challenge like a synth that runs so some very low power
> (9V battery, solar power ???) or design to maximize on some other
> parameter.

Yeah, I've also considered other limitations, but I felt this one was another
interesting take at it. Maybe I am just bored with how most synths are
designed, not as much challenge as such. I don't know.

However, one of my main point about it is also that by bending curcuits you
bend your brain and force yourself to move out of ordinary patterns of thinking
and ordinary patterns of use of various phenomenas. Now, this is when you learn
more on how things actually work if you got enought energy to analyse what's
wrong.

> There might be some fun in making a parts list for what I'll call
> the "Apollo 13" challenge... where you have to engineer some circuits
> using only the parts in that kit. You assume that you are 100,000 miles
> from home... and you simply cannot get ONE more resistor, transistor, etc. no
> matter how hard you wish.

Indeed:

AAAAAHHHHH! We're circling around the Moon and there's not synth here to play
and tweak - how do we build one and how do we tune it?

> Or maybe an absolute minimum component synth ?

Another challenge. The Paia Gnome has pretty much bang for the little buck
spent on HW.

> Anyway, for me I don't have the time to pursue synth circuits that are
> likely to perform less well than more traditional approaches.
> 
> And I bet you don't have time either, Magnus...  ;^P

True!

> (but its nice to dream...)

Indeed. And when I have inspiration I come up with stuff like my VC-ADSR for
instance.

> PS: I would consider the 4007 seriously. Because when I was a tech
> (just starting out) we had to fix a circuit that had failures of the 4007
> very often. It was VERY early in the CMOS process, and the 4007
> was used as an analog gate.
> 
> There were so many failures (I think now, related to ESD pretection being
> inadequate) that the 4007 got a very bad reputation.
> 
> I 'solved' the problem by taking a fresh tube of 4007, and remove ONE chip.
> (all other techs were watching - what is this crazy guy doing?)
> 
> and drop the brand new chip into some clear exoxy they were parching the
> floor with.  I then gave a 'lecture' to the remaining chips in the
> tube "If you chips cause us any more trouble, we will bury you ALIVE like I
> just buried your brother here..."
> 
> And there was never any problem after that. Voodoo electronics.
> 
> After that, whenever some tech had a problem with his circuit, he would
> go to the burial site (floor) with a rag and wipe the dirt from the floor...
> so that everyone could see the chip again....  This was thought to cause
> 'good luck' for the repairs...   ;^P
> 
> So I would not rule out the 4007 as being NO fun. I think it is a
> LOT of fun...   :o)

Hehehe Hihihi.... You're killing me.... Tihitihihihihi.... Ack Pftp! ;O)

Voodoo electronics is fun. Like the "repair" of a flakey $6000 DSP system, with
FIR-filters unexplainably selfoscillate do pops and other strange stuff, with a
2 cent standard resistor. It wasn't VooDoo, it was just real insight, but the
manufacter never got to know why they had a flawed product. Why is another and
much more scarrier story (let's say we learned when feedback did not lead to
consequences we apprechiated hearing about).

There's loads of stuff which may seem "VooDoo" but realy isn't.

Cheers,
Magnus