design/build/test/implement: a slightly better approach?

[dano12]

There are few things about building stompboxes that have frustrated me over the last couple of years—things caused by the transition from breadboard to test pedal to permanent pedal and things caused by the fact that the basic building blocks have to be done over and over again.

As I've been thinking about this, I've tried to think through a better approach to going through the design/debug/tweak/test/finalize cycle. Here are the things I would like to solve:

1. Breadboard/Real Test disconnect: When I come up with something interesting on the breadboard, I want to try it out in my rig with my amps and other pedals, etc. Doing this from the breadboard is a major pain, especially if I want to make the design portable and try it live or hand it off to other players for comment. I can't take my breadboard around, so I have to move to the next tier: perfboard (hate it), vero (hate it), or etching a real PCB (too tedious).

2. Doing the same things over and over again. How many times have I wired a LED resistor, or a voltage divider, or PSU filtering? Way too many times. It sure would be nice to have these things already done.

3. General dissatisfaction with the options of perf/vero/etching: perf is a pain to me—it has stood the test of time, but I hate doing it. Vero is similar: too much work on cutting traces, counting pads, etc. And etching a board is great if I want to make a batch of something, but hardly expedient for testing and learning.

So, to that end, I've been thinking about a design that solves some of these problems, a design that makes the process easier, more fun, and less error-prone. What I've come up with is a continuation of some other ideas posted here, but perhaps taken a few steps further: the beavisboard.



-Idea 1: Use a pad/trace pattern that gives the advantages of vero and perf for prototyping, but makes things easier and quicker to build. So the main area of the board has something akin to existing prototype designs with various pad/bus patterns. The interesting thing here is that could be multiple versions--the main design area could be vero or perfoboard instead of what I've proposed.

-Idea 2: Build the standard design patterns into the board: LED pulldown resistor, power supply filtering, and a voltage divider. Solder some resistors and caps into the pre-designed areas and that is done. Don't need those? Simple, just leave the components out. The components shown are pretty standard values, resistors for the LED drop, voltage divider, and PS filtering. Add a few caps to the PS filtering and its done.

-Idea 3: Solve the problem of having to hard-wire the circuit into a pedal for "away-from-the-bench" testing. Currently, it is a lot of work to take a design and put it in a true-bypass box with jacks and power supply. I've done it way to many times, and there has to be a better way. So the edge card connector is introduced. Using a predefined pin-out, I can build enclosures that I simply plug the board into. Of course, pots remain a problem, but if I have a template box for 1, 2, 3 etc. knob designs, that's pretty easy. Note that the use of card-connector is OPTIONAL, you don't have to use that to enjoy the other benefits of the design.

-Idea 4: There could be two or three sizes for this board, the standard simple one shown for fitting in small MXR type enclosures, and a larger one with ten pins (bi-polar supply, etc.) for bigger boxes.

I'd really like to hear feedback on this idea; as previously mentioned, other folks have taken steps in this direction, but I think with a community-based designed, we could all benefit from having a standardized platform for making the process easier and more fun.

Moving forward, (and this is pretty unknown at this point) my ultimate goal would be to have a vehicle to mass-produce these boards, and make them available at cost to anyone. The design will be in the public-domain, so there is not the commercial issue hanging over the project.

So, what do ya think?

[R.G.]

See:
The FxBus, from 2000 (http://geofex.com/Article_Folders/FXbus/fxbus.htm) and the modular phaser (http://geofex.com/FX_images/Modlr_phase.pdf) as well as

Modularity is a good idea, for all the reasons you mention. The problems with modular systems are:
- People have no familiarity with them.
- Adding controls and displays in a modular fashion is tough; see the comments in the Fxbus about controls.
- It's tough to do sidechains and loops modularly.
- Packaging is an issue for anything except garage versions where hanging-garden wiring is OK. There's always the issue of what goes in the open spaces and how big the backplane is. See http://geofex.com/Article_Folders/FXRack/fxrack.pdf

[Gus]

I would maybe add more PCB circuit fragments like single or dual opamp, power and resistor cap connections,  Transistor and bias resistor PCB traces if you are clever you could lay it out for different bias networks and voltage gain stage or buffer FET or BJT.......,  Distortion fragments like a FF section.  Maybe 1/2 open holes the other fragments

[frankclarke]

If we wanted to standardize on a generic layout board, something like that would be useable, certainly. There is a kind of stripboard which corresponds to the plastic breadboard I have, so you can breadboard with your production layout. You can have your plastic breadboard hardwired into a box with jack sockets, power, volume control and so on. That allows you a design cycle on your breadboard which translates directly to a hardwired shippable version. I say cycle because the first build will have issues, so  design/build/test/ I would prefer to be solder-free. Implement would be easier if you could whack the breadboard layout onto hardwired as idiotically as possible.
So a discussion on engineering the build cycle would be great.

[dano12]

See:
The FxBus, from 2000 (http://geofex.com/Article_Folders/FXbus/fxbus.htm) and the modular phaser (http://geofex.com/FX_images/Modlr_phase.pdf) as well as

I've read both of those articles several times and they present some very interesting and forward-thinking approaches. I think perhaps I am trying to solve a different set of problems here.

I'm not trying to address the modular question, nor approaches to circuit snippets tied together in a modular fashion. My goals are a lot more pedestrian: find a workable alternative to vero, perf and etching that is useful during the overall lifecycle. The card edge connector simply alleviates the need to hardwire all those pesky IO connections into a pedal shell, it's use is optional and not intended to facilite a modular solution.

Modularity is a good idea, for all the reasons you mention. The problems with modular systems are:
- People have no familiarity with them.
- Adding controls and displays in a modular fashion is tough; see the comments in the Fxbus about controls.
- It's tough to do sidechains and loops modularly.
- Packaging is an issue for anything except garage versions where hanging-garden wiring is OK. There's always the issue of what goes in the open spaces and how big the backplane is. See http://geofex.com/Article_Folders/FXRack/fxrack.pdf

All tremendously valid points, especially the pot mounting issue. But again, not trying to solve the modular problem.

I think in a nutshell that I'm really trying to fashion a workable, efficient, and semi-standardized alternative to vero/perf/etch for a specific set of tasks in overall process.

[dano12]

I would maybe add more PCB circuit fragments like single or dual opamp, power and resistor cap connections,  Transistor and bias resistor PCB traces if you are clever you could lay it out for different bias networks and voltage gain stage or buffer FET or BJT.......,  Distortion fragments like a FF section.  Maybe 1/2 open holes the other fragments

Interesting ideas. One nice thing about the pad pattern shown is the two right-to-left bus bars. An opamp straddles them really nicely and if you use the for V+ and ground, the connections to the opamp are really easy.

[dano12]

If we wanted to standardize on a generic layout board, something like that would be useable, certainly. There is a kind of stripboard which corresponds to the plastic breadboard I have, so you can breadboard with your production layout. You can have your plastic breadboard hardwired into a box with jack sockets, power, volume control and so on. That allows you a design cycle on your breadboard which translates directly to a hardwired shippable version. I say cycle because the first build will have issues, so  design/build/test/ I would prefer to be solder-free. Implement would be easier if you could whack the breadboard layout onto hardwired as idiotically as possible.
So a discussion on engineering the build cycle would be great.

Stripboard matching the breadboard sounds like a great idea. Hmmm.....<gears turning>

[AceLuby]

Rehashing an old thread because I like where this is going (love the search!!).  I also find it a pain to go through the cycle multiple times (and I've only done it a few...) because it is the same step no matter what...

At Radio Shack the other day I picked up a breadboard to start monkeying w/ my own designs and there were a bunch of perfboards w/ the same layout as the breadboard I bought.  It was easily big enough for 2-3 projects so I only bought one, but it should be a simple drop in once I get a prototype working.  This will make the transition from design to 'functional testing' (ie, playing it in a 'live' setting, letting others play it, etc...) far easier and should streamline the process a little more.

Maybe I'll work on a standard way to set these up on this specific board.  If I can get it up and running smoothly (and it is actaully easier) I'll post it.