Need CMOS patcher with a lot of I/O. Ideas?

[cslammy]

I need to create a CMOS patch bay for a Lunetta noise project.

There are 12 sources and 2x 5 input bays that need to be patched.

I was going to use 4051B's controlled by Arduino NANO but even at that (8 to 1) it'd be a lot of chips, at least 10 + nano + mux + buffers + power which means a fair amount of PCB space.

Is there another way to do this with lower parts count? So, Some sort of super 4051?

[JovianPyx]

There is CD74HC4067 which is a 16 channel analog mux. It works with a supply voltage from 2 to 6 volts and it is surface mount. That really only combines 2 eight channel analog muxes (plus a 2 channel analog mux) into one chip. You didn't post a schematic of your design so I can't see it to comment on possible simplifications.

http://www.ti.com/lit/ds/symlink/cd74hc4067.pdf <-- datasheet.

Even at that, it will likely be "too many parts". You can either use "too many parts" or reduce your design.

Maybe others have a more clever design.

[PHOBoS]

I'd need a bit more info on what exaclty you like to achieve. Also, are the signals digital ?

[cslammy]

[PHOBoS]

ok, I understand what you want to do now.

Since all the signals are digital you could route (and even process) them through the arduino itself. For this you can use shiftregisters for the inputs
(74HCT165) and outputs (74HCT595) or wire some directly to the arduino depending on how many pins you have available. Of course the supply voltage
of the whole circuit has to be 5V if you do that. Actually, you could just use level shifters between the in and outputs and power the rest of the circuit of a
different voltage.

Using muxes is an easier solution coding wise and you don't have the risk of the arduino doing anything to the sound. However, you'd need a LOT of chips
if you want every possibility. Actually some kind of matrix would be preferred but that still leaves 120 nodes which is an awful lot to control. So yeah, I think
routing signals through the arduino might be the best solution.

[cslammy]

[PHOBoS]

good luck with that (I mean that in the most positive way)

You could of course also use a matrix of switches. Latching pushbuttons (with an LED or mechanical indicator) would be nice for this.
Hmm those old style radio buttons would actually be ideal (like this but with 12 switches), so it mechanically limits it to one output
per input. Adding multiple signals is probably extra fun though (don't forget to add diodes).

[cslammy]

[gabbagabi]

/* two cents start */

the basic idea was to solder some coins on top of each other to get a socket (pic1)

for the matrix you now could imagine a two-sided PCB where you have solderpoints for the coins on each side, one side vertical, other side horizontal connected

if you then plug a banana plug, you have a connection, right?
i would expect that some offset disances here and there are needed
maybe the use of two PCB on top of each other to give it more strength?

/* two cents end*/

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[cslammy]

Interesting g.gabba as always. Coins eh? You always have good ideas!

I am going to mess with this in different ways. I understand that the Ghielmetti matrix costs a fortune (hundreds of dollars?) if you can find it at all....which I can't. So I'll see if I can some up w/ something DIY. If I come up with anything that sorta works I will write it up on the blog.

[cslammy]

OK I am starting to mess with Cmos 4051s mux, maybe for this.

This question arises from trying to build a real world module out of the Simulation at the bottom of this post:

http://audiodiwhy.blogspot.com/2018/12/virtual-bread-board-simulate-your-trip.html

Question:

if you guys were designing a circuit for a modular synth using a 4051 to switch between CV's would you buffer:

--The signals coming into the 4051 (not logic--I mean the CV's I am selecting with the 4051)
--The signal coming out of the 4051
--Or both?


I figure I need to buffer the output? So one TL071?

My reasoning, and yes, I may not know what I am talking about

The inputs of the 4051 are FETs and so are the TL071's inverting and non inverting inputs. But I'd use as a want to make sure nothing downstream from the 4051 sucks too current out of the switch, due to a ground fault or other issue with another module fed by the 4051 switch.

hence the buffer, single TL071 let's say.

What do you think?

[Steveg]

Hi cslammy, For CMOS switches and muxes like the 4051 you don't need any buffering as long as the chips fanout limitations are respected. If you want it for isolation you could use a 4050 for digital signals or a single transistor wired as an emitter follower for analog signals.

If you don't need full any-to-any matrix switching you might consider having a number of busses. A pair of 4051s connected pin 3 to pin 3 gives you a single bus with 8 inputs and 8 outputs. If you put a transistor between the two 4051s you also have isolation. You can connect a single source or sink to several busses and add more as needed.

[CHRISKELLY]

Some great advice there Steve

[blue hell]

Also .. when doing matrix stuff .. I've no idea if you can actually buy such chips .. but there used to be CMOS matrix switches / cross point switches (used for telephony) ... ah AD has something they still make : https://www.analog.com/en/products/ad75019.html - 16 x 16, not like really cheap tho. And my CMOS book suggests CD22100 for a 4 x 4 switch or CD22101/CD22102 for a dual 4x4 (for use with balanced signals).

[piedwagtail]

Could be done with a cheap chinese CPLD development board; my adaption of Richarius's 4015 matrix used as such.


http://electro-music.com/forum/topic-69221

the last post is the actual programming file. Muxs are available as schematic symbols.
VHDL or Verilog is the proper method but Lunettas are simple enough to string together in the schematic programmer.

R

[ixtern]

[synaesthesia]

You still want to patch the connections manually, but get rid of long cables, right? How about using one double male pin header per input (length is given by the number of possible inputs) and make the connection with a small jumper pin. Connect all inputs to the pins on one side of the header. The pins on the other side are connected together as output. Just take care that you only use one jumper pin per row.

BTW, the schematic you have has a short between Q1 and Q3 of the 4040 IC. That doesn't seem right.

[fetideye]

it is not the most usual practice, I know. but it is intentional.
by patching the 4040 outputs together there are cool interactions in the sound.

one day I'll try to achieve this in a more sophisticated way, for example by automated mixing / switching (4060) or maybe buffered by diodes / transistors.

[Grumble]

[piedwagtail]

That's a nice little Christmas gift Mr.Grumble!

Do you use Circuitmaker?

Don't like the look of this especially when DJ is making the claims

https://www.eevblog.com/forum/altium/busted-altium-deliberately-crippling-circuit-maker/

R

[Grumble]

I didn’t made it, just provided the link

[cslammy]

Thanks everyone for all the input.

i will tackle this two fold; first, analog wise, see if I can make a poor man's putney switcher (I have sent proof of concept PCB's, 2x16 point switchers, off to be fabbed, and bought some gold plated "pins" off Ebay to make the connections). I don't hold high hopes for this, but, for the time and money invested, it's worth a shot.

Second, in the digital domain and probably more likely to succeed: is a 11 x 1 I2C CMOS switcher from Maxim, MAX4571EUD+, which I requested a couple of samples of.

https://datasheets.maximintegrated.com/en/ds/MAX4571-MAX4574.pdf

The 4571 should do the trick as I see it. I figure since we are going 12 x 5 twice, I can use the 11x 1 to a MUX (4051) or maybe a 4066. that goes to the 5. Close enough! I'll make something work....

[fetideye]

exciting!

I recently build one noise version with a 4070 patch bay. this gets cool results!
(this was a feature on a early version of my noise synth, I had some pcb's left)

this is what it looks like: (2mm banana jacks)


it is no automatic switcher, but it is very fun to play with.

Note: my newest noise pcb (v6c) no longer connects the 4040 outputs together.

[cslammy]

Still working on this. I am now on the 3rd revision of the patcher PCB, still can't come up with something I like.

Fellow e-m member mvcl turned me on to MUX506 by TI, that's the next thing I'll try...http://www.ti.com/product/MUX506. Sounds like a very useful chip for Audio DIY.

bipolar (!) 16 input (!!) sort of version of the 4051.

Also, I have a cheap putney patcher working. Not sure of how durable it is but for this project it'll probably work! I'll do a blog post about that.

[cslammy]