Author Topic: Pedal switching matrix with the AD75019  (Read 15016 times)

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Harold

Re: Pedal switching matrix with the AD75019
« Reply #160 on: November 07, 2016, 10:15:22 PM »
I figured out a while back, I really had pretty much all the sub assembles for this already, except for the exact input and output buffers I want to use - but even there, I have something pretty close.  And of course, I have the development board I've shown here before (at least, I believe I have), so really it's just finding the time to sit down and build up the boards, and wiring all the bits together to test it.  I'm hoping to get to it as soon as possible

Gabriel, that's exactly what I'm facing now!  ;D

I tested the AD-chip with an ULN2803 that lit up LEDs, the buffers are yet untested, the power supply is a make shift on breadboard, and the whole assembly with wires running about; and it's probably one big antenna.

I got as far as it's "ready to test" and then I decided I was too tired ;)
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G. Hoffman

Re: Pedal switching matrix with the AD75019
« Reply #161 on: November 16, 2016, 12:10:07 AM »
I figured out a while back, I really had pretty much all the sub assembles for this already, except for the exact input and output buffers I want to use - but even there, I have something pretty close.  And of course, I have the development board I've shown here before (at least, I believe I have), so really it's just finding the time to sit down and build up the boards, and wiring all the bits together to test it.  I'm hoping to get to it as soon as possible

Gabriel, that's exactly what I'm facing now!  ;D

I tested the AD-chip with an ULN2803 that lit up LEDs, the buffers are yet untested, the power supply is a make shift on breadboard, and the whole assembly with wires running about; and it's probably one big antenna.

I got as far as it's "ready to test" and then I decided I was too tired ;)

Yeah, I'll have to design a PS, but for now it will run on the bench supply. 

I've kind of been distracted by, well, life, and also the Deluxe Reverb transformers I had sitting in a drawer.  Mostly life, though.  It's been a shitty year.


Gabriel

potul

Re: Pedal switching matrix with the AD75019
« Reply #162 on: November 17, 2016, 08:17:49 AM »
Hi All,

I've been reading this thread for some time and now I'm starting to gather some parts to do some experimenting with crosspoint matrix switches. Regarding buffering.... what would be the lowest parts count/simpler buffer system? Can I use a CD4069 to build 6 buffers?

Mat

G. Hoffman

Re: Pedal switching matrix with the AD75019
« Reply #163 on: November 23, 2016, 09:18:31 PM »
Hi All,

I've been reading this thread for some time and now I'm starting to gather some parts to do some experimenting with crosspoint matrix switches. Regarding buffering.... what would be the lowest parts count/simpler buffer system? Can I use a CD4069 to build 6 buffers?

Mat

I'm pretty sure that's a logic buffer, and not really appropriate for analog signals.  AMZ FX has a page about basic buffer designs - http://www.muzique.com/lab/buffers.htm.


Gabriel

potul

Re: Pedal switching matrix with the AD75019
« Reply #164 on: November 24, 2016, 02:12:47 AM »
I was thinking on usign it as an opamp, the same way we do for distortion pedals.
The CD4069 I have are unbuffered (I think)

Mat

pdavis68

Re: Pedal switching matrix with the AD75019
« Reply #165 on: November 24, 2016, 03:55:37 AM »
Hi All,

I've been reading this thread for some time and now I'm starting to gather some parts to do some experimenting with crosspoint matrix switches. Regarding buffering.... what would be the lowest parts count/simpler buffer system? Can I use a CD4069 to build 6 buffers?

Mat
I just made one of these and need to make another: http://www.muzique.com/news/jfet-buffer-on-stripboard/

Low part count jfet buffer. Same thing, but different values and more compact vero layout. http://s76.photobucket.com/user/IvIark_2006/media/Layouts/Vero/JFETBuffer.png.html

I'm about to build a single chassis pedalboard that has a number of pedals built in (I have 12 built so far). I think if I were going to do something like this, I'd integrate it into that pedalboard. I'd probably use a 2-digit LED and use a microcontroller to handle the logic. I imagine I'd want it to work something like this:

You'd have an up-down buttons to set the digits on the LED. They'd indicate which "program" you wanted. A program would be a mix of inputs and outputs in a specific order.
So you'd go to the program # you want to create a setup for. There'd be a "Set Program" button that you'd press and it would turn off all the pedals. You'd then go through and active the pedals in the order you want them. The microcontroller would track the order. Then click the "Set Program" button again and that would store the pedal assignments and order.

Simply set the program number and it would active the pedals for that program in that order.

Not too far off from like a Floor Pod or something like that.

PRR

Re: Pedal switching matrix with the AD75019
« Reply #166 on: November 24, 2016, 07:28:50 PM »
> Can I use a CD4069 to build 6 buffers?

Yes, that is the minimum hex "audio" buffer I know. But CMOS hisses, also distorts some. You need 2 caps and 2 to 4 resistors per buffer (unless you are clever/lucky and don't mind pops when switching). Six transistors is hardly more to build. Three TL072 is only a few more pins and worlds cleaner.

potul

Re: Pedal switching matrix with the AD75019
« Reply #167 on: November 24, 2016, 08:34:57 PM »
Thanks PRR,

this is exaclty the kind of info I was looking for. PRobably TL072/74 is the way to go.
In fact, I just realized that because I need 8 buffers, I would need two CD4069. Moving to two TL074 doesn't look much more pin counts.

I will start playing without buffers and when I have the concept working I will decide what buffer architecture to implement.

Thanks again!