SN Voice mixer control?

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

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.

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

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

elmegil · Posted: Sun Mar 17, 2013 8:40 am Post subject:

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.

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

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.

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

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

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

elmegil · Posted: Thu Mar 21, 2013 4:59 am Post subject:

Care to share a schematic of your mods? Smile

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

Glad it worked out!

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

elmegil · Posted: Thu Mar 21, 2013 5:32 am Post subject:

Dur. Too early in the morning :/