[sdiy] 566

[Scott Stites]

Hi List,

I have to agree with Cynthia and John - Thomas Henry's 566 book is a great read
and has some really nice applications for the 566, and a lot of it applies to
things other than 566 based stuff.  I agree, his style of writing is quite
refreshing as well - there's always a level of enthusiasm in it that to me is
infectious.  Interestingly, he does mention somewhere in there that it might be
possible to apply the same tricks to an IC like the 8038.

During my Christmas break DIY orgy, I tried Thomas' V/Oct 566 circuit, and I was
*very* pleasantly surprised.  I'd planned to use the 566 VCO's as built in
modulaters and carriers in a ring modulator module, with the VCO outputs being
externally available as well - I was picturing it as being a useful, fairly
non-accurate VCO for applications where absolute pitch wasn't a requirement. Come
to find out it was a helluva lot more accurate than I had envisioned, and sounded
great.  I played it with the keyboard, and it sounded pretty dang good for no
more of a circuit than it was.  True, it may go flat at the higher ranges, but it
would be an excellent VCO for sequencer applications, not to mention S&H and
joystick control.  And his sine shaper circuit (which could be used for any
triangle VCO core) produced the absolute purest sine I've ever come up with.

As a bank of VCO's, it probably wouldn't be that practical - it does require a
few more IC's (all very common) than just the 566.  

Cheers,
Scott


On Tue, 27 Jan 2004 09:16:26 -0800, Cynthia Webster wrote:

> 
> Hi Gang!
> 
> Thomas Henry still has the 566 VCO chips at $6.00 each.
> 
> Warning: These are really quirky chips hat need special support
> circuitry to be useful as VCOs and Henry's little book on
> using them in circuits is highly recommended!
> 
> (Great reading too! I find his style to be the most conversational
> form of technical writing I've seen.)
> 
> http://www.midwest-analog.com/catparts.html
> 
> Best to all!
> 
> Cynthia
> 
> 
> 
> on 1/27/04 7:30 AM, Scott Gravenhorst at music.maker at gte.net wrote:
> 
> > jbv <jbv.silences at club-internet.fr> wrote:
> >>> Do you mean the 556 (dual timer)?  566 is anything but cheap
> >>> now that it's transmuted into an isotope of unobtainium.
> >> 
> >> I really mean the 566...
> >> A few months ago I got 40 pcs on ebay for less than $30...
> >> 
> > 
> > Ok, "cheap" for you then.  Well, sure, it would work that way.
> > But if you want each one to track an expo CV, you need expo
> > converters for each one (or lots of good sample and hold
> > circuits with one expo converter and the driving logic).
> > 
> > If you don't care about voltage control, i.e., just a bank of
> > oscillators each with a frequency pot, then the 556 dual timer
> > actually makes more sense, depending on exactly what the
> > intended use is.  If it were me, I would not use the rare 566
> > for non VC applications.  Also, if you decide to use the 556
> > (dual timer), there may be problems with soft synch, especially
> > between oscillators on the same chip.  There may be a CMOS
> > version of the 556 which would be somewhat better.  If not,
> > there's always the 7555.
> > 
> > I gave up on finding the 566, it's a single chip tri/square
> > VCO, which is something that can be done fairly easily in other
> > ways.  LM13600/LM13700 and I assume other dual OTAs as well can
> > also be a one chip solution.
> > 

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