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 Forum index » DIY Hardware and Software » Thomas Henry designs
SN Voice mixer control?
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doobedy



Joined: Jan 12, 2009
Posts: 19
Location: Los Angeles

PostPosted: Sat Mar 16, 2013 3:11 pm    Post subject: SN Voice mixer control? Reply with quote  Mark this post and the followings unread

So I just finished up an SN-Voice in Eurorack, and it's using sneakthief's idea of switches to send 5v to mixer A/B/C. I really want to make a companion panel to be able to control them with logic/audio/cv whatever.

Can anybody think of an easy way to convert audio/bipolar cv/10v logic gates to 5v logic easily? So I could just have a panel with 3 jacks labeled mix A, B, and C and safely input anything to control stuff rhythmically. LEDs would be neat.

I had two ideas, no idea how to do either really, but a half-wave rectifier and some sort of diode clipping at 5v might work, or something like the cd4066 I think could switch +5v off or on, but I'm not sure if it will happily switch just feeding it untreated bipolar signals.

I'm worried about sending the SN76477N modular level signals where it expects 5v logic, don't want to blow anything up.

Also, if there's anything else I can bring out to an expander, I'm all ears. 3 jacks is kind of sparse! Maybe the noise clock could be cool, or a saw shaper.

Here is a bad picture just for fun of the panel I'm using, courtesy of clarke68 Very Happy

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



Joined: Jan 12, 2009
Posts: 19
Location: Los Angeles

PostPosted: Sat Mar 16, 2013 3:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hmm, maybe this is exactly what a comparator is for.
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elmegil



Joined: Mar 20, 2012
Posts: 1449
Location: Chicago
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PostPosted: Sun Mar 17, 2013 8:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Another option: CD4050. it's made so that you can drive the inputs higher than Vcc so that it is commonly (?) used as a level shifter.

If you want to have more of a schmitt trigger response, you could use a 40106 inverter to square up the input and a 4049 to buffer/level shift/invert back.
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sneakthief



Joined: Jul 24, 2006
Posts: 529
Location: Berlin

PostPosted: Sun Mar 17, 2013 5:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

How about a couple of Schottky diodes and a 10k resistor? Here's a thread about protecting chip inputs so the voltage stays in a safe range:

http://www.eevblog.com/forum/projects/pic-input-protection-using-a-zener-diode/msg21840/?PHPSESSID=33bbdf2e2a88957db87cce882680f1ca#msg21840

I just tested this out and it works fine. I used a BAT46.

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doobedy



Joined: Jan 12, 2009
Posts: 19
Location: Los Angeles

PostPosted: Sun Mar 17, 2013 5:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

sneakthief wrote:
How about a couple of Schottky diodes and a 10k resistor? Here's a thread about protecting chip inputs so the voltage stays in a safe range:

http://www.eevblog.com/forum/projects/pic-input-protection-using-a-zener-diode/msg21840/?PHPSESSID=33bbdf2e2a88957db87cce882680f1ca#msg21840

I just tested this out and it works fine. I used a BAT46.


Thanks guys.

Sneakthief that does look like it might cover all the bases with the fewest parts...clipping the negative half, and limiting the top half to a little more than 5v.

Out of curiousity, did you try it with an SN Voice? I'm hoping it's not too picky, and that's all it will need.
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doobedy



Joined: Jan 12, 2009
Posts: 19
Location: Los Angeles

PostPosted: Wed Mar 20, 2013 10:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Welp, I tried it with the SN Voice and it was 100% successful, all the way up to audio rate pseudo-mixing. Took anything I threw at it, even the triangle out and I learned about diode clamping and level shifters along the way.

Now I just need to make up a companion panel and order some more Schottkys.

Razz
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elmegil



Joined: Mar 20, 2012
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PostPosted: Thu Mar 21, 2013 4:59 am    Post subject: Reply with quote  Mark this post and the followings unread

Care to share a schematic of your mods? Smile
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sneakthief



Joined: Jul 24, 2006
Posts: 529
Location: Berlin

PostPosted: Thu Mar 21, 2013 5:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Glad it worked out!

elmegil: check out the link I posted earlier in this thread.

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elmegil



Joined: Mar 20, 2012
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PostPosted: Thu Mar 21, 2013 5:32 am    Post subject: Reply with quote  Mark this post and the followings unread

Dur. Too early in the morning :/
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