Switching systems ?

[KB]

Hello all

How easy is it to implement switching of a series of loops using a PIC? 

Along time ago there was a web sit "Frank clarkes zone of distortion".  On the site there was something called the switch witch, which allowed the switching of loops in and out of the circuit. I also think that there was some limied memory which allowed you to set up a number of patches and then recall them.  IIRC there was no mention of Midi.  The thing worked  on some PIC what type I do not know.

The site is now long gone, altough you can get some info about the Mutirat and various tubscreamer mods via the wayback archive.  Unfortunatly the files about the switch witch have all been pulled by a robot. 

Does anyone have any information about such a switching system.  Has anyone designed a switching loop system that allow say 8 loops and switching of amp functions?

I have read RG's articles so I think I have some of the basic ideas of what is required to implement a system but controlling it all is where I loose the thread.

I have limited knowledge of programing PIC's (I still use Fortran 77 - realy should learn a new language) but I have been reading basic articles about consturtion of PIC programers that I found on the web. Anyone have any pointers where I should look??  I think what I am actually looking for is a NOBEL's MS-8 which like all good gear is no longer available.

I would appreciate any dirrection that anyone can give.

Best regards

Kevin

[rmo]

It could easily be done with a PIC and some relays. It could be as simple or as complex as you like. I would just use dpdt relays, you can drive relays from a PIC by using a transistor of some sort, I've done it using transistors from the NPN assortment at radioshack.

You could just have 8 seperate relays running from 8 different outputs on the PIC, and set up different combinations in the software, with some way of selecting them. You'd have to have them hard wired in a certain order, but you'd be able to switch them in and out easily.

For switching amp functions, you could use a single pole relay, just hook it up to the PIC using a transistor just like the effects loops.

As far as visualizing which effects are selected, you could have an lcd, or just use 3pdt relays and use an led.

This site will show you how to connect the relays, it also has a lot of info on programming PIC's.
http://www.mikroelektronika.co.yu/english/product/books/PICbook/7_05chapter.htm

[KB]

Thanks rmo

that link is very interesting, lots of information there.

I found this site while googling   It seems if you look long enough someone has beaten you to it...

http://www.jimkim.de/html/index.htm

Looking at the looper project in the guitar effects seems to be what I want.  Maybe it is of interest to other people.

Kevin

[RaceDriver205]

If you want to know a bit more about PICs, http://www.mstracey.btinternet.co.uk/pictutorial/picmain.htm is pretty good.
PICs have a limited instruction set of about 35, which is good for those with limited knowledge of assembly language.
If you want ridiculous numbers of instructions that do every thing, AVRs are pretty good. I really don't know which manufacturer is better.

If by 'loops' you mean sending the guitar signal to separate loops (8?) as controlled by the corresponding number of switches (8?), I could probably help you there. It could be done without PIC programming, and with few parts. Tell us if your interested.

[KB]

Thank you RaceDriver

I think I have a lot of reading to do.

What I am trying to sort out is having a number of loops eg 6 (for individual pedals) and a couple of switches (amp channel and reverb or possibly control an A/B switcher.

But would also have a limited amount of memory so you can set up patches and just recall the bank and patch and get your effects (and amp) combination with the stomp of one footswitch.

The Looper project in the link I posted in my reply to rmo seems to do this.  It also has the hex. code for the PIC which would make the project easier for a PIC virgin like me.

At the moment I am looking into that one, but thanks for your offer.  I will post anymore info when I find it.

Cheers

Kevin

[RaceDriver205]

Sure, but you have one of those "MIDI controllers", right? If so, absolutely do that looper.

[Peter Snowberg]

Since the post was bumped by David a couple of days ago, I've done a bit more work on my Crossbar switcher. The CrossBar-1 has a single input, 6 loops switchable in any order, and up to 4 outputs. Unfortunately it's going to be at least a month or two until I can turn this design into a PCB.

[David]

Since the post was bumped by David a couple of days ago, I've done a bit more work on my Crossbar switcher. The CrossBar-1 has a single input, 6 loops switchable in any order, and up to 4 outputs. Unfortunately it's going to be at least a month or two until I can turn this design into a PCB.

Ohhhh, suuurrrreee!  Blame it on me!   

Actually, not letting this one fade away is WORTH some abuse.  Peter, between the ASMOP and the Crossbar, I believe a practical, programmable switcher/looper is now within DIY reach.  Frankly, I'm really motivated to see it happen.  I'm sick of that freaking GT-3.  It just ain't makin' it.  I gotta get back to analog effects land.  No problem with digital control, but I'm coming to the end of my rope with digital effects.

[KB]

Hi Peter, David

I think I should take the blame.  I found the thread "Midi talk" started by fikri only after I stated this thread.  Both threads seem to be asking questions about a similar idea, sorry I should have read more before posting questions.

Peter.
Very interested in the crossbar project, so will wait for more information.  Missed that one for some reason.

David.  Like you I have had it with digital multifx.  I have used RP6 and RP10 not the Boss stuff, good for delay and reverb but never liked there OD and Distortion.

The like I posted to

http://www.jimkim.de/html/index.htm

uses a LS7447 to drive a 7 segment led display anyone know anything about them or a possible substitute as I cannot find them listed at mouser, or futurelec.  I tried Google but I end up with the tail light assembly for a 1960 car

Kevin

[RaceDriver205]

Search for 74ls47 at futurlec. They have them.

[KB]

Search for 74ls47 at futurlec. They have them.

Thank you.....

[David]

Also, the following is a link to the datasheet for the 7447:

http://www.datasheets.org.uk/pdf/7447-datasheet/7447-datasheet.html

It's a common-anode LED digit driver.  The common-cathode CMOS equivalent is the 4511.  I'm using this right now in an experimental bass pedal controller I'm working on.  The 4511s will handle digit display chores so I don't have to use interrupts to prevent flickering.  I'll just put the binary nibble on the ABCD inputs to the 4511 and be done with it.

[RaceDriver205]

Yeah, the 4511 is a good part. Ive used it in conjunction with a shift-register to allow a uC to control a 7-seg using only 2 pins. VERY usefull.

[Peter Snowberg]

If you're using a uC, you can use a high current shift register like the TI TPIC6B595 to drive the display directly without the need for the hardware decoder. That gives you the ability to do several letters and patterns while taking one less chip per digit. You also get control of the decimal point with a 2 wire interface for minimal setups and a 3 wire interface for "glitchless" operation. 

The 7447 is a power hog and it won't do hex digits either.  I finally ended up using 2716s with a truth table in the first 16 bytes

[David]

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