[sdiy] Searching for a VC Clock schematic ......

[Rykhaard D.A.M.I.A.N.]

:) :) :)  Many thanks for the answers from the 3 of you, guys. :D

>>My idea is based on a CMOS clock around a single CD40106 Schmidt
>>Trigger Inverter, along with a CA3080 TOA, for the VC portion.
>
>Alas the horse has bolted. The CA3080 is now extinct, so the best idea
>is not to make new designs using it :(
>
>Ken

I'm doing ok on this one here Ken, as I myself still have 37 in stock, and 1
of my 3 suppliers in the city still has just over 400 in stock through the
province. :)  With my own stock, I'm good for at least 6 more months.  I
have a further question, at the bottom of this reply though ......

On 12/24/05, Megohm writteth:
>Why not the 4036? I haven't tried it. Is it not stable enough or
>something? You can VC a 40106 oscillator using a vactrol for the
> feedback resistor. Drawback is the lag time of the vactrol. I made a
>bank of six and used one as a clock for awhile. Here's a pic with links to
>the sources: >
>http://home.comcast.net/~peng5002/modules/sixsquarespage.htm<http://home.comcast.net/%7Epeng5002/modules/sixsquarespage.htm>

The 4036??  I just went searching through Google for it, but I'm not
entirely sure if I found any info on it or not.  :(  Repeated searches with
different search terms (CD4036 by itself, with manufacturer; with datasheet
..... only seemed to come up with places that are allowing you to seek
quotes; mention of discontinued; a couple said 4 bit shift register .......
Had you meant, the CD4046 phase locked loop?  I've chosen not to go with it,
only because I don't have any. :)  And my 1 supplier here, that stocks CMOS,
carries it, but they're a fair travelling distance away - for immediacy in
building. ;)  (I.E. - lazyness in getting to. :O (shy grin))

A problem with Vactrols for me, is availability. :(  My 3 local suppliers
don't stock any, at all. :(  That's kept me away from experimenting with
Buchla circuits. :(

>Ray Wilson's musicfromouterspace site has some circuits that use a >40106
clock. I don't remember if they're VC-able.
>
>peng

Ray's sequencer is what started me ON the CD40106. :) :)  A wonderful ship
for buffering, in the CMOS end of things. :)  I've picked up 6 of the chips
in the last 2 weeks, as I'm adopting the idea of it for all of those
purposes, as well as for sharpening the squarewaves up when in use for
triggering such. :D
The 'Master Clock' that I have breadboarded at the moment, is built around a
single unit in a 40106.  I'd thought of using 1 chip, for 6 clocks in my
coming sequencer panel, for redistribution (and combination, if possible)
for many of the sub-modules in the panel. :)  Hence - the VC idea, last
night.  (Further on this, in my reply to Scott. :) )

On 12/24/05, Scott Gravenhorst <music.maker at gte.net> wrote:
>
> If what you want is a clock where the frequency is controlled by a
> voltage, then what you need is a VCO with a level shifter and driver.  I
> have one on my site, but I the VCO I used is a linear pitch CV type, not
> expo.  The top row of parts in the schematic is the linear voltage to
> current converter.
> For expo, this needs to be replaced with you favorite variety of
> exponential voltage to current converter.  (I don't use expo).


Here, for everything, I'm using only Expo. :)  I'm not worried about
compatibility with anything, as I just sold my dead MS-20 to a friend in
Winnipeg who collects 'antiques'. :)
And - almost all of the schematics that I reference from or work with and
modify, are exponentially based. :)

http://home1.gte.net/res0658s/fatman/vcngvco.html
>
> The VCO part is just the datasheet triangle VCO.  The square output from
> the VCO goes above and below ground, so I put it through a diode and then a
> transistor to amplify it, then to a CMOS inverter gate as a final buffer.
> From there it can clock whatever I want.
>

The idea of making a VC clock with the 40106 that I like so much is the
severe LACK of parts, for the clock. :D :D  I've been wanting to keep things
as minimal as possible, as I'm hoping to squeeze as many sequencer module
portions and variations into 6U of rackspace that I can.
With my desires for VC and interconnection in as many areas as possible -
I'm going to be having a lot of circuitry occuring behind my panel. :O
That's why - the smaller the better for each module portion. :O :)  Using a
single 40106 element for a clock - I could have up to 6 of them available.
With each of them being VCable - a Master Clock (external to the machine, or
one of it's own clocks), could be the main clock timing to each of the
others used, which are then individually modified with their own speed
controls / etc.  All within a small amount of circuitry. :)
Otherwise, I'd just go back to a 1V/Oct VCO as a master clock.

Ahhh!  I just remembered a trouble here, as well. :(  Clock speed.  I've got
2 x 7 bit dividers going into the sequencer panel as well, for clock
divisions; boolean logic control (with logic gates), etc.  With up to 14
bits of division from a Master Clock - to have the slowest speed at a
musically useful speed, I'm looking at a Master Clock speed requirement
between 10khz and 100khz.
My discrete Tom Gamble VCO4D is stable up to about 30khz, when it starts
loosing amplitude.  (1V/octave stable, up to about 9Khz, as far as I've
tuned it.)
So that rules it out, for higher frequency controlling as a Master Clock.

(Lack of matched transistor pairs availability outside of the CA3046 has
kept me away from other discrete VCO circuits).

Now a trouble that I thought of last night, with my using the CA3080 to VC
the speed of the 40106 clock:

The output of the 40106 clock, would go through a 100k/220r divider into the
positive input of the 3080, to control the amount of current that's charging
the grounded cap, at the input of the 40106.
My thought last night though - when the output of the 40106 switches Low,
will the output of the 3080 (with diode, to prevent any Negative voltages
from coming out) be at Ground, so that the cap can discharge?  As with the
40106 output being Low, it's input will be High, with the charge on the
cap.  It's only other 'exit' is to the Output at Low.  But - the 3080 will
be in the way, of it's discharging, wont it?

I would go and breadboard it right now - but we're headed out for many
Christmas Eve visits today and tomorrow and my girlfriend, wouldn't think to
much of things, if I headed up to my 'lab'. :(  Soooo ...... I can only play
with the circuit in my mind - hence - asking for help. :)

Now - if this is not possible, with the 40106, then I just may come back to
a standard Integrator / Comparator setup with VC, for doing it simply. :)
(Actually ....... using 1 of the 40106's for the Comparator section, would
make that square much sharper, and I'd just have to block any negative
voltage from the Integrator output ........ more for the brain to fiddle
with til I can prototype on the breadboard again. :D )

Thank you greatly for your help guys!  I do hope that you have a wonderful
Xmas Season. :)  (warm smile)

--
Take care,
Warmth and Peace,
Ryk

http://deathlehem.bravehost.com/damian.html - D.A.M.I.A.N.;s webpage - Dec
2105 update
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