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 Forum index » DIY Hardware and Software » Musical Interfaces
Voltage controlled SP3T Switch
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null object



Joined: Aug 14, 2010
Posts: 3
Location: Marrickville Sydney Australia

PostPosted: Fri Aug 20, 2010 4:14 am    Post subject: Voltage controlled SP3T Switch
Subject description: Modifing a Roland SH101 Transpose Switch
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Hi everyone!

This is my first post so to make it memorable I would like to ask smrt people for some help.

I would like to modify my Roland SH101's Transpose switch so it can be controlled by CV.

I have some ideas how this could be accomplished if the switch was a simple on/off but it is actuall a 3 way swith which works like this.

Oct up - pin 2 and pin 3 are shorted together
Oct middle - pin 2 is not connected
Oct Down - pin 2 and pin 1 are shorted together

Posted Image, might have been reduced in size. Click Image to view fullscreen.

I hope you can understand the above example.

I understand there are CMOS type Switches but they rely on a logic trigger to switch them.

I am unsure how I can split up Control voltage to trigger the 3 switch positions.

I was thinking of 2 comparator circuits one that would read voltages between say 3.5 to 5 volts to trigger the Oct up switch
and another reading say 1.5 volts and below to trigger the Oct Down switch
and then maybe an AND Gate to either do nothing when getting a trigger from either of the two comparators or switch to the Oct middle switch if not getting a signal from either comparotor.

I hope this makes sense.

I know electronics only by studying onlint tutorials and looking a circuits diagrams.
I understand most of the logic of circuit design but I don't know all the tech stuff.


So does anyone have a schematic for something like this or feel ilke designing one up?

I would be happy to make a board up with 4 or 5 on it and sell them on. My mate has his own CNC router and makes up his own boards for his stuff he builds.

Thanks again and I hop my first post to you all will be welcomed.

Nath/Null
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cagnalerano



Joined: Oct 26, 2008
Posts: 14
Location: italy

PostPosted: Sun Aug 22, 2010 4:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

why do you want that switch to be CV controlled? as far as I know the sh-101 just has one oscillator, so you just have to add 1V to the CV

am i missing something?
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null object



Joined: Aug 14, 2010
Posts: 3
Location: Marrickville Sydney Australia

PostPosted: Mon Aug 23, 2010 11:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi cagnalerano,

Probably what your missing is the knowladge of how I like to make music.

Sure I could just add the voltage to the OSC CV to jump octaves but I like to create an amount of random chance.

I'd like to run the LFO into the transpose switch CV and set it to random!

Maybe just run my Roland system 104 sequencer into the transpose switch.
This way I could play one synth off the 104 sequencer and the SH101 would transpose in time with the other synth.

I'm interested in the direct relationship of machines controlling other machines.

Computer sequencing bores me to tears.

I try to make machines create the music by their own interaction with each other.

I also have lots of old synths with switches. If I could CV all their switches I could create more control in my system.
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adambaby



Joined: Nov 18, 2009
Posts: 10
Location: Queensland, Australia

PostPosted: Thu Oct 07, 2010 12:31 am    Post subject: Reply with quote  Mark this post and the followings unread

I hear what you're saying Nath - I manually flip the transpose control on my Korg 700 when recording a sequence to spice up a repeating riff, it's very arresting.
External control is a great idea.

_________________
Adam Inglis
A Disco Ate My BABY!
www.adambaby.com
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ultrashock



Joined: Dec 10, 2009
Posts: 40
Location: Vienna.AT

PostPosted: Fri Dec 03, 2010 12:42 am    Post subject: Reply with quote  Mark this post and the followings unread

null object***

your task is feasible, here is the start point for you, but you have to mess around with binary codes inputs for 4051 (A, B, C):
http://hem.bredband.net/bersyn/VCO/8p2ch%20VC%20switch.png
just remove one 4051 and you will have VC 8 channel selector. by powering CV from 0 to 10 volts you will get the switch from 1 to 8 channel on output (or vice versa). By coupling 1-2 inputs, 3-4, 5-6 and 7-8 you will get 4 channel selector. This is the simpliest way.
To make it 3 channel you have to think out hot to realize the voltage input to the A B C using op-amps as invertors (if the input is more than 12V it is "true" or 1, if lover than 5 it is "False" or 0. I'm not sure about the volts, but you have to check them out since they depend also from the Vee, Vdd or Vdd supply of the 4051 chip.
KR,
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