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Showing posts from August, 2018

Arduino based SYNTHDVM--Up and Running.

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Hello again, yes it all works.

The SynthDVM is as far along as I think i will take it.

For anyone who wants to catch up:

Part 1  is here--as I try to master the art of undocumented Arduino clones and parts

Part 2 is here. Design goals for the project.

Part 3 is here. Let's get the OLED meter to look "analog"

Part 4 is here.  clobber that op amp!

About the DVM, It reads DC from about -10.5 to +10.5V with an accuracy of better than 1% throughout its entire sweep--very close to .5% for say 5V and pretty much dead on between +/- 3V.  As they say (I say)  in audio DIYland "good enough".

If I designed a custom PCB for this, which I see little point in doing, with a good layout and large ground plane, it'd probably perform better but it's not bad for a sandbox PCB, a nano, and a handful of opamps.

There were some evenings of cursing over this one, I had some ripple on the Opamp + and - rails I couldn't get rid of, but I finally re soldered a few traces here an…

Synth DVM part IV: Neat Arduino Trick--good for Audio DIY--Crush that op amp!

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I finished (!!) my arduino based Synth DVM, it worked last night anyway; need to do a few final software tweaks then will post.  As always I am sure someone can improve it, but it's working well.

You can see part 1 here--I try to master the art of undocumented Arduino clones and parts

Part 2 is here.  Design goals for the project, Blah blah ginger blah blah.

Part 3 is here.  Let's get the OLED meter to look "analog"

How it looked about a week ago...front panel an "alubase PCB" from PCBWay....the PCB is already bolted on. Along the way I found a cool and easy way to make an Arduino treat audio like it's running through 4066 cmos switcher. Maybe better?

It's a nifty enough trick that I thought it should have its own post.





The hack goes like this:
If you've screwed around with Arduino for more than a few minutes you find the things don't like negative voltages w high current on their analog pinssince my SynthDVM is chock a block with negativ…

40106 Quad opto coupled VCO--Lunetta Lives!

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All hail Lunetta Synthesis--the CMOS anything-goes way of thinking about Audio DIY?



One thing that appeals: Stanley Lunetta is from the California Central Valley, same as me--from my reading his studio was about 40 miles from where I was recording back in the day.

Does this prove that we Central CA folks aren't all farmers and politicians?  Does it need to be proven? Growing up I remember a great music scene, at least in the 70s. Makes sense--there was very little else (legal) to do!

OK: In honor of Lunetta Synthesis and all Central Valley artists I decided to fab a quad VCO one of the great CMOS chips, the 40106.

I've messed with this chip before but this was my first attempt at doing something this, well, VCOish.

I went through a few generations of experimenter boards by designing in Eagle, and sending off to EASYEDA for a test fab.  I almost have given up on perf'ing things. It's faster and easier for me to have boards fab'd abroad, sent back to the US, and if …