Help with intro to active onboard controls

[stevewf]

Hi again, Nutz.

A while ago I posted a a passive circuit that required a 9P3T switch; ungainly at best, nonexisting at worst. (There are other issue with that circuit, too, but for now I'm focusing on the switch).

It occurred to me that maybe the switch could be done electronically instead - a single three-position physical switch that in turn controls 9 solid state switches.

I've been sniffing around basic electronics tutorials online, learning enough to understand that... I don't quite understand. I see NPN and PNP transistors and a need for biasing the DC voltage in order to capture full AC signal... I see FET circuits. The tutorials almost all focus on amplifying signals, but at this point, I'm trying to learn about On/Off switches.

Could somebody please share a schematic or wiring diagram that shows how to use necessary components to, in effect, turn that 1P3T switch into a 9P3T switch?

Knowing that I'll be adding a battery to the guitar, I'll probably want to take advantage of that and add other active controls like blend, volume, tone, etc, and later even overdrive... but that's later. For now, it's just the switch.

[sumgai]

steve,


First, I congratulate you on both your desire to increase your knowledge, and your perseverance in obtaining that goal.


But for now, I'd like to take a moment and caution you on some things, things about which you aren't aware because you're looking at a forest, and aren't aware that you're missing all the trees.

I'm mainly speaking to your gamboling around and finding whatever seems attractive and fulfilling, and that's not a good thing. You have a goal in mind, ramping up your switch knowledge, and going off on a wild ride with Mr. Toad, i.e. transistors, FETs, biasing, all that good stuff.... that's getting in your way.

So let me bring this to you: focus on, and search for, logic control.  By this I mean logic as in "If I were doing this in an analog way, how would I "Solve For X"? So to speak..... Now you have a starting basis for how to implement that solution in electrical circuitry, usually meaning integrated circuits. But wait, there's more!

At this point, I'd be highly remiss if I did not send you off to Arduino-land, or Raspberry Pi-land, or any of the other single-chip microcomputer systems out there. These devices are nothing more than programmable logic controllers, greatly simplified. The languages used are stripped down versions of high-level stuff, and even if you've never looked at anything more than BASIC, or perhaps HTML, you'll still be able to understand what's going on. With a little help from your internet-based friends, of course.

The real advantage to something like this is not just that they are completely open, and very powerful in their own right, but they are also small, to the point of being nearly the size of a humbucker pickup. And they don't have to take a lot of power, if you do some assiduous shopping around - they can be very battery friendly.


And finally the most important part...... Don't let me steer you away from the road you intend to travel. I'm only pointing out the path I would take, were I 65 years younger, and not yet an amateur radio operator (HAM). You, of course, have a different mindset, and so you may well feel like my advice is not gonna cut it. Fine with me, nobody elected me the superior being with sees-all, knows-all infallibility, I get that. So be it.

But, and here's where we all come in, when you do run across a "rabbit-hole" that you simply must traverse, then we're here to answer questions of the nature you've propounded above, no sweat.

HTH






sumgai

[kitwn]

I've spent some time over the last couple of years looking into the use of microprocessor controlled switches for use inside a guitar. I haven't actually designed and built anything in detail as I have decided to concentrate on becoming a better player of the instruments I already have rather than build anything new just yet.

There are digitally controlled analogue switches around designed for routing audio. Lots of options from various manufacturers at differing costs. The CD74HC4066 is an inexpensive option to look at for starters. Get the datasheet from Texas Instruments.

You can also buy digitally controlled potentiometers for volume and tone controls as well as blending levels of signal from different pickups. These can replace the switches in many places when turned down to minimum. Endless rotary encoders are then used in place of mechanical potentiometers to pass instructions to the controller.

The total cost could easily be little more than a complex 5-way mechanical switch, which would not be required (though my plan is to use one of the simplest 5-way switches as a mode selector if I ever get round to building anything).

Controlling all this stuff without an overly complex array of switches on the guitar requires a microprocessor (Arduino would be a good option as Sumgai suggests) and thus some learning of how to program it. You would also need to learn about minimising the power consumption of the Arduino (basically achieved by having it spend 99% of it's time asleep!) and choosing other devices for low power use.

If you want to go down this rabbit hole you will also have to learn how to design and make your own circuit boards and how to solder surface-mount components. None of this is especially difficult, nor are the tools prohibitively expensive but it will take some time to get across the various skills required if you're starting from ground-zero.

I have some notes on possible components to use and a user-friendly control layout if you are interested. Beware, this kind of thing can get addictive!

Kit

[stevewf]

Thanks guys. I'm not in any huge rush at this point, so sumgai's advice resonates. 
kitwn, I see there's a wide range of learning waiting for me. Started with switches, will need to expand to rotary encoders, maybe further.

There's a guitar in mind for this, yes. But it's been playable as-is, passive, for years and can wait longer.

Off to Arduino "class" (browser-style) I go!

[sumgai]

Jul 31, 2024 21:04:35 GMT -5 kitwn said:

There are digitally controlled analogue switches around designed for routing audio. Lots of options from various manufacturers at differing costs. The CD74HC4066 is an inexpensive option to look at for starters. Get the datasheet from Texas Instruments.

Sage advice, studying the fabled 4066 is a very good place to start in your search for "how does a digital switch work?" But when it comes to actually implementing a breadboard full of components, you might look a little further afield for better performance, signal-quality wise. The ADC6412 is a near-drop-in for the 4066, but if you're starting from scratch in your design, it outperforms the old-school chip by just about every measure that counts.

HTH








sumgai

[stevewf]

Progress report: so far I've skim the surface of arduino -- like piece of space junk whose orbit is decaying skims the atmosphere. That, in turn, has sent me off to scrape the surface of things like voltage-following OP-Amps and AC circuits on SSRs and more, with yet more awaiting. I begin to see that arduino brings a ready-made platform in various forms, and looking at examples can help me gain a better grip on approaching the goal of designing guitar control setups. And thanks, kitwn and sumgai, for the leads on specific ICs that provide 4 independent switches that are suitable for audio signals - it's a good taste of what I'm after.

Next: a little more digging until I can see what components I'll wanna gather for learning, experiment-wise (my favorite kind).

[stevewf]

Jul 31, 2024 21:04:35 GMT -5 kitwn said:

I have some notes on possible components to use and a user-friendly control layout if you are interested. Beware, this kind of thing can get addictive!

Kit

...and, I'll probably take you up on that offer once I understand the terrain better!