Arduino based pickups switching

[kraftzeug]

Hello everyone.
After successfully trying the Red Special wiring from John Hewit, I was wondering if pickup switching could be managed by a microcontroler. 
I'm pretty sure this could lead to a simpler user interface since a basic 5 way switch could be used to dial in favored configurations.
I first imagined using static relays, but soon realised it would use a huge amount of space into the guitar.
Reed relays won't be of any help here I suppose since there would be electromagnetic noise.
Therefore, I'm here to ask you what kind of electronics would be best suited for audio switching. 

[Deleted]

Guess transistor
Interesting how you used a Arduino tho

[newey]

We've discussed using digital switching in the past, but I don't think anyone here has ever tried it. I'll try to find the relevant thread on that.

[Deleted]

Guess first question is what you using to control

[reTrEaD]

Jan 3, 2020 2:28:02 GMT -5 kraftzeug said:

I was wondering if pickup switching could be managed by a microcontroler.

There's already a commercial product which does that.
Music Man Reflex "Game Changer"

Jan 3, 2020 2:28:02 GMT -5 kraftzeug said:

Therefore, I'm here to ask you what kind of electronics would be best suited for audio switching.

I'm not sure what's in the Game Changer but I would guess, something similar to these: Bidirectional Analog Switch. But those are based on some very old technology. Over 40 years old. I reckon there are newer devices which accomplish the same task, but have lower ON resistance and lower leakage and capacitance in the OFF state.

[kraftzeug]

Jan 3, 2020 12:08:25 GMT -5 reTrEaD said:

There's already a commercial product which does that.
Music Man Reflex "Game Changer"

Yep. It exists.
It's just a bit costly and overpacked. 

I imagined something simpler, where you could choose some favored configs in the arduino, and use it with just a switch to choose.
Something that would'nt have to be used with a computer once it is setup.

Consider this: Brian May mainly used 2 pickup configs and most guitar players aren't too comfortable when there are too much switches and potys.

I'm pretty sure that with just an arduino, a couple of transistors and a standard strato toggle it could work with a price reduced a lot.

The only part I'm struggling with is knowing which kind of switching device would be best suited for audio switching.

Mosfets? IC?

I'm lacking the necessary knowledge.

[reTrEaD]

Jan 3, 2020 17:37:07 GMT -5 kraftzeug said:

Mosfets? IC?

The heart of the 'relays' would be FETs and definitely Insulated gate (mosfet) rather than jFet because isolation between the gate and channel is crucial.

An IC package where multiple devices are on a single chip would make things more compact than having discrete Fets and driver circuits. That's why I linked to the 4066 Bidirectional Analog Switch as an example.

[kraftzeug]

Jan 3, 2020 23:20:12 GMT -5 reTrEaD said:

The heart of the 'relays' would be FETs and definitely Insulated gate (mosfet) rather than jFet because isolation between the gate and channel is crucial.

An IC package where multiple devices are on a single chip would make things more compact than having discrete Fets and driver circuits. That's why I linked to the 4066 Bidirectional Analog Switch as an example.

Thank you! This was a really clear explanation.

I have found some modern ICs, like this one which could certainely do the job, but are meant to be used in computers or phones, therefore they are really small and their contacts not meant to be soldered by a rookie builder.

Maybe the one you linked to would do the job perfectly after all (old tech is not necessarily outdated)

[reTrEaD]

Yes, surface mounted devices aren't appropriate for hand-soldering. You'd definitely want something packaged in a DIP.

Jan 4, 2020 2:21:05 GMT -5 kraftzeug said:

Maybe the one you linked to would do the job perfectly after all (old tech is not necessarily outdated)

It would work for a proof-of-concept but the performance wouldn't be stellar. On resistances in the double-digits are slightly problematic for this application and the leakage from gate to channel add up when you have multiple devices added to each pickup lead. So you'd want something a bit better than the 4066, for your final product.

[perfboardpatcher]

Jan 3, 2020 2:28:02 GMT -5 kraftzeug said:

Therefore, I'm here to ask you what kind of electronics would be best suited for audio switching. 

I had to look it up. I'm not saying they're best suited but the components that I a long time ago harvested from an old Yamaha 8-track were "digital" transistors.

DTA114E-D.PDF
DTC114E-D.PDF
DTC143E-D.PDF

[kraftzeug]

I have a feeling the max4622  would do the job. They are only 5ohm on-resistance and have a voltage range sufficient for it to be controlled by the arduino.
As a proof of concept, I think I would choose cheaper ones like the max4619 with 10ohm on-resistance should do it.

I have other projects ongoing, but I will certainly try it soon and will come back with schematics and arduino sketch to share with you.

Thank you all for your advices..

[doogs]

Just reviving a bit if a necrothread, apologies.

This has already been done, as arduino based and pi based, by a chap going by the moniker Grateful Frog.

He though went much further and made volume /tone microcontroller enabled. Doesn't work with fitting too well within the guitar, but has also created an app to control the electronic side via Bluetooth or a stomp box.

Just Google pyguitar grateful frog and you'll get the pages.

I recently contacted him via twitter as I'm considering trying to go for switching via a rotary encoder / pi or arduino and chip switching. I need to finish my current project first though.

Interestingly, it was 4066 chips he used, but I have seen others that would probably work.

[kraftzeug]

Apologies accepted ^^

In fact, i'm working on a new guitar, and i'm considering adding those functionalities soon.

Thank you for the GratefulFrog link, I'll certainly have look to how he done this although i really don't like the huge ugly add-on he made to his guitar. There's plenty of room in most electric guitars (if you know how to use a router) to make it discreet.

[kraftzeug]

So.. I had another quick check at gratefulfrog.org/Arduguitar/arduguitar.html and to its doc

I was amazed at the simplicity of his overview schematic but i then realized it was not meant to do series/parallel switching, unlike what i planned at first when i talked about John Hewit's Red Special Wiring.

It made me reconsider my whole project and I think i will settle for the simple route for my first try at analog switching.

I'm not sure whether tone and volume controls on a per pickup basis is really useful though, but i still need to check his videos to make my mind.

Anyway, thanks again Doogs!

[doogs]

The add on was a bit much, but as a proof of concept it shows what can be done. With a little planning I'm sure you can work it out.

If my current project works out OK I may move on to an arduino controller with a rotary encoder for pick up selection and a 1" screen. I would retain the analogue potentiometers though. A lot to learn first.

[kraftzeug]

Hi there.

I finaly got my hands on a handful of Max4619.

I just made a test with an arduino and some leds, and phase switching is working as intended! 
This is for the theory and the programming of course. I now have to make a prototype with real pickups to see if I have any noise with these analog switches.

I'll let you know how it turns out once it'll be done. It might take some time though, as i'm currently working on a new guitar as my main project.

[Jaga]

Oct 4, 2020 4:51:57 GMT -5 kraftzeug said:

Hi there.

I finaly got my hands on a handful of Max4619.

I just made a test with an arduino and some leds, and phase switching is working as intended! 
This is for the theory and the programming of course. I now have to make a prototype with real pickups to see if I have any noise with these analog switches.

I'll let you know how it turns out once it'll be done. It might take some time though, as i'm currently working on a new guitar as my main project.

Hi! You have some news? Interested in the topic!

[kraftzeug]

Sorry, I have no more news as I have worked a lot on other things.
As i promised, i'll post results once i'll have it done with real pickups, but it might be not anytime soon.