Lunetta-Lab board

corex · Joined: Mar 02, 2010 Posts: 114 Location: Las Vegas

Nice writeup man, it looks great!

trav · Posted: Sun Aug 31, 2014 6:24 pm Post subject:

Wow, nice job!

This is a great idea, very neatly done, and all finished and boxed up within such a short time too. Very tempted to look through your designs and come up with a similarly nice, compact "semi-modular" design.

Let's hear a couple of patches!

commathe · Posted: Sun Aug 31, 2014 7:44 pm Post subject:

Quick question: looking over the schematics there are a lot of places where you use a double connector and what I would expect to be ground is not attached to ground but to the connector instead. What's this for?

synaesthesia · Posted: Mon Sep 01, 2014 12:19 am Post subject:

The double connectors are for all digital output signals. Sometimes this is hard to see in the schematics because I simply placed the two connector symbols on top of each other. By having two pins for each output signal, I can route two cables per output to other inputs. For example, send an output to another clock input and to an LED driver. Should I need even more fan-out, there are a few 3-pin connectors on the top row that can be used to split a signal once more.
Not sure where you miss a ground connection, I hope I didn't forget one. The resistors, capacitors, the switchable resistor network, and the vactrol output are floating so that they can be connected in series or parallel to other elements.

synaesthesia · Posted: Mon Sep 01, 2014 2:44 pm Post subject:

@trav, you wanted to hear a patch from the Lunetta-Lab, so I sat down to patch something... Have a look at my post about the Crazy Fiddler and listen to the result.

commathe · Posted: Mon Sep 01, 2014 6:16 pm Post subject:

That all makes sense now! It was the EG that was really throwing me off.

goldenhours · Joined: Aug 28, 2014 Posts: 3 Location: Dublin, Ireland

Hi,
This is my first post in this forum. I've recently become fascinated by the world of CMOS and Lunettas, and synaesthesia's Lunetta Lab board is just great, and I am thinking of making something similar. Something very portable, patchable, which lets me explore and learn about the possibilities of a range of chips (and I also use diy instruments in live performances so it may well end up there, too!).

Personally, I'm not sure about using male pin headers on the board, so I'm looking at using female receptacles and male jumper cables.

As far as I can see, there are two basically different types, one like this: http://img-europe.electrocomponents.com/images/R7655521-01.jpg , which comes in fixed sizes and is a little more expensive, and the other type like this: http://img-europe.electrocomponents.com/largeimages/R2677416-01.jpg , which are cheaper and are snappable to whatever size required. Does anyone have any experience with the second type? Because it seems to be more for holding ICs rather than jumper cables, how well do the cables sit in the sockets?

Any comments/suggestions would be much appreciated.

corex · Joined: Mar 02, 2010 Posts: 114 Location: Las Vegas

Regarding pin headers, I've tried a couple different models of Mill-Max machined pin headers, such as Mill-Max 801-43-064-10-002000, and I've also tried the cheaper stamped-pin kind such as 3M 517-929974-01-36-RK.

I prefer the 3M part. Both parts are easy to cut to size, but the 3M part is deeper and the test lead stays seated better.

goldenhours · Joined: Aug 28, 2014 Posts: 3 Location: Dublin, Ireland

synaesthesia · Posted: Sun Sep 07, 2014 1:08 pm Post subject:

In my experience the machined pin headers are good for ICs, but not good to hold wires at all. The first type is a bit better to hold wires, but still doesn't give very good contact because they are built as the counterpart for PCB connector pin rows, which typically have a square cross-section. The wires used for breadboards and most male Dupont cables have a round cross-section.

corex · Joined: Mar 02, 2010 Posts: 114 Location: Las Vegas

I use Molex 16-02-0114 (crimp terminal for AWG 24), which has a square profile, to build my jumpers. They fit a little better than the round ones but there are still longevity problems -- I think some unreliability and rework is just inherent in pin-header design like this.

goldenhours · Joined: Aug 28, 2014 Posts: 3 Location: Dublin, Ireland

Thanks guys, this is all really helpful. I guess before I make any big decisions and part orders I'll get a few different options and try them out.
I really like how the builder of the "tinysizer" made the patchbay in a similar way (http://www.anyware-instruments.de/images/tinyinfo/modules_home/tinysizer_0,5mb.jpg), but it seems it took him a long time to find the right sockets that work with standard round jumpers (http://www.anyware-instruments.de/analog_modular_synthesizer_firstideas_english.html)

PHOBoS · Posted: Tue Sep 09, 2014 1:59 pm Post subject:

synaesthesia · Posted: Tue Sep 16, 2014 3:06 pm Post subject:

Three more changes I would make if I would build this again.
1 - add two more oscillators, you can never have enough
2 - replace one 4040 by another 4520, one long counter is enough
3 - add one or two push buttons (non-locking) for triggers/resets
4 - increase the volume resistor pot to 20K or 50K
5 - change the clock burst circuit and add pots for length and frequency
6 - add a few separate diodes to be used for diode-resistor logic
7 - change the connector rows from 3 to 4 pins, and have more of them
8 - drop the analog circuits, like the filter, this is more flexible on a breadboard

droffset · Posted: Wed Oct 15, 2014 2:48 am Post subject:

Hi there, this is a very cool build! I love this way of patching things together, even though the more dense patches can get a little confusing, it's great to have a giant lab in a small form factor. Good stuff.

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

20121031_124023 by drOffset, on Flickr

revtor · Joined: Oct 05, 2005 Posts: 79 Location: NewJersey, USA

This is great!!!!! Thanks a lot for your work!

It is really nice to have a central location of schematics that will play nice together.

~Steve

synaesthesia · Posted: Mon Jan 12, 2015 12:35 pm Post subject:

Thanks for all the feedback. I am having lots of fun with this build. And yet, the enclosure for version 2 is already done and the modules are in the planning stage. I will start a new thread for V2 as soon as the modules are near completion.
One of the biggest advantages is breadboard compatibility. It is so much more convenient to try something new if you have complete building blocks already available and easy to connect to. Especially pots, they don't fit well in breadboards.

hexagon5un · Posted: Thu Mar 26, 2015 5:53 am Post subject:

Wow. I just went through the PDF schematic. Holy crap, that's well done!

I really like the LED banks and the 4066-based resistor switches. It's creature comforts like that which make working on a modular different / easier from working on a breadboard.

How useful do you find the EG and vactrols? What do you use them for? Do you need more?

More pots? VCAs? Or are you going to go so anti-analog that you won't use them?

That frequency doubler circuit looks great. I've never seen that one before. What do you think about using pots / vactrols for the adjustable delays? (Not that you can stop me from building one that way anyway even if you hate it. Smile

)

I find it hard sometimes to give up on the everything-must-be-voltage-controlled mentality. I want to control every facet of every sound rather that just letting the machine be what it is. You seem to have acheived some kind of nirvana! Kudos.

revtor · Joined: Oct 05, 2005 Posts: 79 Location: NewJersey, USA

This should be a PCB!

like those analog / digital trainer boards, or those Radio Shack 300-in-one kits..

synaesthesia · Posted: Thu Mar 26, 2015 1:40 pm Post subject:

PHOBoS · Posted: Thu Mar 26, 2015 2:22 pm Post subject:

that looks promising Shocked

do you have a lasercutter, a steady hand or used something already existing ?

synaesthesia · Posted: Fri Mar 27, 2015 12:56 am Post subject:

I have a very good friend with a CNC mill. The frame is made of 8mm MDF (medium-density fibreboard) and the upper and lower inserts are made of diffused plexiglass.

commathe · Posted: Fri Mar 27, 2015 3:16 am Post subject:

I love it! Twisted Evil

PHOBoS · Posted: Fri Mar 27, 2015 3:29 am Post subject:

a CNC mill of course, I forgot about those. I gues you're going to put LEDs behind the plexiglass ?
and I'm wondering if the middle part could be used as a trigger using a piezo disc.

synaesthesia · Posted: Fri Mar 27, 2015 9:39 am Post subject:

Patience please... Very Happy

I don't want to spill all the beans too early. I plan to document the frame and each of the eight boards (6 visible modules, 2 boards behind the frame) in a separate thread.
The middle part is a speaker already mounted behind a soft white fabric. You bet there will be RGB LEDs behind the top part, two of them.