Jim Patchell's Control Voltage Splitter

funkyfarm

Does anyone ever give a try to the Jim Patchell's Control Voltage Splitter ?

http://www.oldcrows.net/~patchell/misc/splitter.html

Dan Lavin · Posted: Mon Apr 30, 2007 5:21 am Post subject:

Interesting. I drew up a similar circuit for a new keyboard I'm working on. I am using a joystick controller with pitch on the X-axis and two separate modulation types for the Y-axis. The plan is to have the Y-axis hooked to -V and +V and have the circuit split 0 to +V voltages for positive Y-axis and split 0 to -V for negative axis. The 0 to -V voltage would then be inverted for positive voltage control. Each CV would drive 2 separate VCA's. One siginal would be a sine or triangle wave and the other a low frequency noise wave like the minimoog.

This circuit would work for that if -V break is set to ground (0V).

Fernando · Posted: Mon May 14, 2007 2:42 am Post subject:

It is very interesting. I stored the circuit time ago but never build it.

I was thinking in a CV processing tool but a couple of months ago I was thinking in it as a noise comparator to produce noise grains.

???

funkyfarm · Posted: Mon May 14, 2007 1:06 pm Post subject:

On my side, it's long time I've been thinking of adding somewhere on a blank panel four sockets : one INPUT socket linked to 1n4148 anode to another OUTPUT socket.
With two of these, I could extract the positive and negative part of any incoming signal... I left this idea because of 0.3Ge and 0.7Si negative clipping...

Anyway, this design is cool !

And I still have to further explore the VC-BREAK part of it !

I've use it as "double gate"

Put +/-5V SQUARE LFO
REVERSE NEGATIVE OUTPUT
When positive gate or incoming signal shuts down, the reversed negative one becomes active...

Nice for adding accent (CV of 292 LPG) and shifted CUT OFF controlling of a couple of filters (stereo fx)

Samples are not best for illustrative purposes, but I can say that I have real fun with this little thing. Wink

Last SWING series sample

Fernando · Posted: Mon May 14, 2007 3:18 pm Post subject:

maybe useful too for processing a random source and get two "related" random signals...

and the -Vbreak controlled by another random signal...

that may be taken from Vo1 or Vo2, scaled with an attenunverter, providing some feedback (correlation) to the thing

' drunken

and up to audio freqs now

(hey, great sgniw!)

funkyfarm · Posted: Wed May 16, 2007 10:16 am Post subject:

asterisk · Joined: Sep 17, 2011 Posts: 17 Location: burlington, VT

so is this kind of a max/min circuit with an adjustable center?

(a fixed max/min is always centered around 0v right?)

diablojoy · Posted: Sun Jan 08, 2012 1:13 am Post subject:

had not seen this one before
nice samples funkyfarm
i think i may try playing around with this one a bit
might even put a couple behind a panel

fonik · Posted: Sun Jan 08, 2012 8:12 am Post subject:

diablojoy · Posted: Sun Jan 08, 2012 4:20 pm Post subject:

will try it first with a tl074
i can use the extra opamp for an extra inverted input
then i can use a positive cv output from a seq to move the breakpoint around
simple enough
maybe an attenuverting offset control could be added also

PHOBoS · Last edited by PHOBoS on Thu Jan 12, 2012 7:16 am; edited 2 times in total

I just gave it a try to see what it really does and then used it to design a
circuit that merges the top and bottom halves of 2 waveforms together.
With the CV/pot you can 'wipe' between the 2 input signals. Because the
ouputs behave inverted (top1+bottom2 VS top2+bottom1) it makes a
very nice (auto)cross-panner.

I'm not sure if this is one of the things hinted in the posts above, but I
think it's a very useful circuit. Smile

edit: flipped the diodes around compared to the previous schematic, more info later.

PHOBoS - Wave Wiper.gif

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diablojoy · Posted: Wed Jan 11, 2012 4:43 pm Post subject:

nice work

I think it is a very usefull cct too well done

so can you try inputting 2 differant wave forms
say a tri and a square at the same and differing frequencies
and check the outputs to see what you get please
scope shots would be nice if you can.
not originally what i was looking for but i know rikhaard
was looking in that direction trying to rediscover something
he did long ago.

asterisk · Joined: Sep 17, 2011 Posts: 17 Location: burlington, VT

phobos,
your circuit looks interesting.
it has 2 outputs, are you saying output 1 is regular and output 2 is inverted version of output 1?
ill have to try to breadboard this one and test it out. seems fun.

PHOBoS · Posted: Thu Jan 12, 2012 10:21 am Post subject: Wave Wiper example graph

asterisk · Joined: Sep 17, 2011 Posts: 17 Location: burlington, VT

that makes sense to me now, thanks for the explanation.

im going to try to breadboard this soon.

diablojoy · Posted: Thu Jan 12, 2012 4:04 pm Post subject:

vladosh · Posted: Thu Jan 12, 2012 5:28 pm Post subject:

I already cut a piece of stripboard Smile

asterisk · Joined: Sep 17, 2011 Posts: 17 Location: burlington, VT

would a TL074/084 quad op-amp work fine in this circuit instead of the LM324?

PHOBoS · Posted: Thu Jan 12, 2012 7:45 pm Post subject:

PHOBoS · Posted: Fri Jan 13, 2012 1:50 pm Post subject: tuning the Wiper

For those brave enough to try it, here's how to test and set the 47K trimpot:

Don't connect any signals to the inputs (incl. CV), better yet connect them to GND.
Turn the trimpot to it's minimum resistance, and the 100K "WIPE" pot to -12V.
You should measure a voltage of roughly +2V on OUT 1 and OUT 2. Now turn
the "WIPE" pot to +12V and measure the outputs, they should now be roughly -2V.
(if you measured a voltage way above and below 2V you could have the
trimpot turned the wrong way. else you need to check the circuit.)

Next, with the "WIPE" pot still at +12V turn the trimpot so that both outputs
are 0V. Now turn the "WIPE" pot back to -12V, the outputs should stay at 0V.
adjust the 47K trimpot if necessary. that's it Smile

(at least for now)

note: the circuit should work fine on +/-15V but you might want to
increase the 220K resistor attached to the "WIPE" pot.

emdot_ambient · Joined: Nov 22, 2009 Posts: 667 Location: Frederick, MD

PHOBoS · Posted: Fri Jan 13, 2012 2:32 pm Post subject:

some more tests in case you don't have a scope and can't see if it's
working correct:

CV source connected to IN1 (pot between +/- 5V is useful for testing)
"WIPE" pot at +12V
OUT1 should follow IN1, OUT2 should be 0V

"WIPE" pot at -12V:
OUT1 should be 0V, OUT2 should follow IN1

CV source connected to IN2
"WIPE" pot at +12V:
OUT1 should be 0V, OUT2 should follow IN2

"WIPE" pot at -12V:
OUT1 should follow IN2, OUT2 should be 0V

for a final test you can connect a DC voltage to IN1 and a different voltage
to IN2. With the "WIPE" pot you should be able to control the outputs
between these voltages (where OUT2 does the opposite of OUT1).

vladosh · Posted: Fri Jan 13, 2012 4:10 pm Post subject:

Here's my layout Smile

, the power conection on LM324 is missing as i'm gonna make that with wire ,simply no space that's how these stripboards are ..
greetings

(fixed layout with pin 5 and 10 to ground)

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PHOBoS · Posted: Sat Jan 14, 2012 6:29 am Post subject:

vladosh · Posted: Sat Jan 14, 2012 6:32 am Post subject:

heh :/
thanks for checking the layout Phobos , i always do that kind of stuff and then wonder ..