DIY octaswitch???

[Ohioisonfire]

I want to try to build something like the Carl Martin octaswitch. I have built true bypass loopers and they're cool but I think some with the DIP switches so that each foot switch allows you to choose a "preset" would be A LOT more useful. Does anyone know how to do this?  I tried looking it up but everything I found was pretty confusing (I don't know very much about building pedals). How hard is it? Thanks..

[R.G.]

Read the programmable footswitch design pages at Geofex.com. I designed this stuff years ago.

There's not a complete design, but it's pretty simple to work out.

[Ohioisonfire]

I've read through it 3 times and it makes almost no sense at all.  I'm not sure why, it's just really confusing.

[R.G.]

I've read through it 3 times and it makes almost no sense at all.  I'm not sure why, it's just really confusing.

If you don't have an electronics and logic background, that could happen.

Tell me which of these don't make sense and we'll work on it.

1. A relay is a device that bypasses/enables an external effect loop. It activates/deactivates on the basis of a signal applied to its coil.
2. Relays are relatively high power devices. It's easier to run them if you put some kind of semiconductor switch in front of them to apply/remove the coil power. When you do this, the transistor can then be thought of as part of the relay; again, you feed it a signal to turn on or off.
3. If you want to turn on a selectable number of relays, you need a way to select just the ones you want. A DIP switch lets you do this, but the selected relays can interact after the DIP switches. For using DIP switches, you need a series of diodes after the DIP switches to keep the selected relays from feeding back to other relays.
4. Once you have dip switches and diode anti-backfeed arrays, one signal to a DIP switch turns on whichever relays the DIP switch says to.
5. If you want on footswitch to turn on at a time and turn off any previous footswitches, you need a 'radio button' style footswitch setup.
6. Radio button footswitches can be had with a mechanical interlock so that pushing a new one turns off all the old ones. This is difficult and expensive to set up mechanically.
7. Doing the radio-button selection in CMOS ICs is much cheaper, but requires you to understand the CMOS chips.

[richon]

I've read through it 3 times and it makes almost no sense at all.  I'm not sure why, it's just really confusing.

It takes time to understad it, but once you do, IT HELP A LOOOOT!!!!

I use it as a guide to find "my" way to implement it and works perfect...  and I MEAN PERFECT....

I've build 2 of this switchers (one with 8 preset for 8 pedals and one with 8 present for 10 pedals and an amp footswitch)

[PRR]

> something like the Carl Martin octaswitch.

Nobody can remember all the products in Banjo Center. Give links so we don't have to rack or hunt.
http://www.carlmartin.com/product%20octaswitch.htm
http://www.carlmartin.com/manual%20octaswitch.htm
Seems to be price-fixed at $415.10.

> I designed this stuff years ago.

The OctaSwitch claims to be "simplified" from some larger "Combinator". Superficially it IS "simple". The bank settings are held in DIP switches, a mechanical ROM (or WORM) memory. This is "less" than your plans.

If I am reading the website right, the Octa does not give you a real-time choice what order the pedals are in. This is set at plug-in. (More elaborate matrix arrays allow arbitrary ordering.)

I took a first crack at the logic:



While the Octa has 8 FX and 8 banks, there is no need to have the same of each. It would be silly to have 2 FX and 10 banks (only 4 combinations are possible), quite reasonable to have a dozen FX and just two banks (you only play two different sounds). But DIP switches are often 8-position, 8 jack-pairs fit a long box, and "Octa" is a catchy name.

The flaw in my plan here is that you must un-stomp one bank to use another bank. If you don't, you get the .AND. of the pedals on both banks. That's not workable live.

You could replace the stomp switches with one rotary switch. To avoid bend-over, beef the shaft and put a foot-pedal on. Twist your foot to select a bank. This unnatural action may be dangerous after a few drinks. You can contrive mechanical links under stomp-buttons so when you start to stomp one, all the rest are reset; such mechanical cleverness is a lot of trouble. (You can buy finger-buttons this way but they are expensive and rarely stocked.)

The most practical way to bank-switch is momentary buttons and some logic. There's clever ways to rig several CMOS gate chips to do this... but for more than 2 banks, today's PIC chips become just as simple and allow further features.

The OctaSwitch also has a buffer and one stereo FX loop.

[R.G.]

Don't forget to use tip-shunt jacks and 'normal' the shunts so that if there's nothing plugged into the jacks, the action of the relay won't make the whole thing go silent, routing audio through something that's not plugged in.

Ask me how I found that one out... 

[SISKO]

 Take a look at this http://generalguitargadgets.com/projects/15-boostersrouters/65-super-simple-switcher

[R.G.]

If you want it for live use, you would like to add to PRR´s design a logic control to the switches so when you press one switch, it disable the last one (hope it makes sense ), so you dont have two "on" switch at the same time.

That would be like the CMOS switch to do one-of-eight in the descriptions at geofex, right? 

[PRR]

> when you press one switch, it disable the last one

That's what "The flaw in my plan here is " says.

> take a look at this

Same issue.

AND if I'd known about that I would NOT have wasted a lot of time mousing lines and dots.

[SISKO]

That would be like the CMOS switch to do one-of-eight in the descriptions at geofex, right? 

Yeep!

> when you press one switch, it disable the last one

That's what "The flaw in my plan here is " says.

> take a look at this

Same issue.

AND if I'd known about that I would NOT have wasted a lot of time mousing lines and dots.

I´m sorry PRR, I didnt see the bottom part of your post! Please, let me edit my post

[defaced]

As pointed out by PRR and others (from the GGG notes file):

One shortcoming of this design is that enabling any Patch does not disable any previously selected Patch(es).

Which is fine, but using CMOS logic circuit on RG's site, and the DIP switch/relay/output jack board in the GGG project, you have what you want.  The GGG site has all of the selection/switching done.  Just add logic (PIC, TTL, CMOS, whatever). 

[mmaatt25]

Hi,

I looked at RG's programmable footswitch when I was trying to make a switching system for a Bass player. I went down the relay route using an Arduino MC to take care of the switch control. That is still a work in progress (struggling with the code). Although I keep being told that relays are unacceptabley noisey for this application and CMOS is better. I will finish it so I can compare the two.

I got side lined by http://members.shaw.ca/roma/ there's a sequential switcher schematic using a CD4017 and  a CD4066.

I put together a switcher that controls four seperate inputs by one momentary switch and three outputs again controlled by one momentary switch using two CD4017 and two CD4066.

Heres the schematic for the output section:



I've posted the full layout here http://www.diystompboxes.com/smfforum/index.php?topic=95572.0

[R.G.]

I keep being told that relays are unacceptabley noisey for this application and CMOS is better. I will finish it so I can compare the two.

Good choice. Relays can be quiet or noisy, CMOS can be quiet or noisy. The devil is *always* in the details.

[mmaatt25]

Is there any signal loss when using CMOS switching?

[PRR]

> Is there any signal loss when using CMOS switching?

"Any"? Yes.

"Any"? Typically 300/100,000 or 0.3%. 0.026db.

[proaudioguy]

I have drawn a basic schematic very similar to the one posted above with the dip switches. I would like to add the ability to swap order of some effects but what I really want is 4-6 presets that engage relay loops and switch amp functions. Jam struggling with how to accomplish this.  I has read the geodes page several times.  Number 7 in RG's post is where I am stuck. There are several diagrams and descriptions on his page but nothing complete or set in stone just presented as ideas.  Great for someone familiar with this stuff. I spent a few hours searching the part numbers already.

Need to work with 9-12vdc
From the dip switch down I have a good plan.  From the momentary foot switch to the dip switch I am lost. I found another thread where someone possibly figured out a Atwater to do this without the CMOS bits but I can't find the schematic. Have no idea what kind of diodes to use to keep the relays from backfeed ing their friends. I have several diodes used for the rectifier in a twin reverb. Perhaps overkill? Not sure if 9v would even pass through these and they are large.  Any recomendations?

[MoltenVoltage]

Here's a link to a guy who is making a DIY Programmable Pedalboard using our 9 Switches module:

http://www.guitarforum.co.za/effects/sonic-titan-programmable-pedal-switcher-%28wip%29/

Here's a link to the module:

http://www.kaom.com/PedalSync_MV_62_9_Switches_module_KIT_p/module_005.htm

No DIP switches required!

[Processaurus]

Here's a link to a guy who is making a DIY Programmable Pedalboard using our 9 Switches module:

http://www.guitarforum.co.za/effects/sonic-titan-programmable-pedal-switcher-%28wip%29/

Here's a link to the module:

http://www.kaom.com/PedalSync_MV_62_9_Switches_module_KIT_p/module_005.htm

No DIP switches required!

Very interesting, Karl!  So is that module pretty much exclusively for this kind of application?  And you make your presets by pressing the footswitch to get into the preset you want to edit, then toggling the write switch, then pushing some of the nine footswitches to set the bypass state of the corresponding nine effects, then toggling the write switch again to store it, and that's that?

[MoltenVoltage]

Glad you like it Ben!

Yes, it was designed specifically to make programmable pedalboards when combined with the MV-57 logic-controlled Relay Bypass modules.

There are 2 ways to program it.

1) You send the Program Value for the particular program (either from a MIDI controller or the 4 Presets chip), then press the footswitches for the bypass loops to either turn them on or off, then toggle the Write switch to store that setup in the current program location (up to 128 programs).

2) If you are using the PedalSync Master Controller module, press the footswitches for the pedals to either turn them on or off, then hold down the
Tap/Pgm button and the Controller will send a command causing the 9 Switches chip to self-program in whatever program location you choose.

Either way, its simple to program.

The Master Controller was designed as a compact module so you could house it in the same enclsoure as the 9 Switches module, although I haven't had a chance to build that version yet.  The best part is the 9 Switches Modules can be used like building blocks to make pedalboard switchers as large as you want, or separate modular programmable loop boxes.

Also, a number of builders are using the 9th switch/output to make a "bypass all" loop.