Tracers, lemme hear you say whattt

[Stickman393]

A'ite. Question.

Let's say you've traced out a circuit. Like, you've got the board, you've peered at the traces for hours on end, used a meter to confirm continuity, and built a schematic from that board.

Whatcha all do to *verify* that your schematic is correct? Make a list of all the different nets and perform a continuity test? Breadboard it and see if it works?

Inquiring minds and all.

 

[rwl]

Related: are there any good tutorials on tracing? I've looked at the tracing journals from Aion and they're interesting but not really teaching me anything.

 

[Nostradoomus]

 

[Feral Feline]

whattt?

 

[temol]

Related: are there any good tutorials on tracing? I've looked at the tracing journals from Aion and they're interesting but not really teaching me anything.

Quite long but interesting

 

[HamishR]

I've only traced a few simple circuits when I've been curious to find out how they were made. To me, if I build what I think I have traced and it sounds much the same I think I have achieved what I meant to. As long as I get a good result I'm happy! Usually I'm tracing something to modify it anyway... I don't think I've ever traced something just to copy it.

 

[PedalBuilder]

Breadboard it and see if it works?

This. If it sounds right, then you probably traced it correctly. I also take advantage of the derivative nature of guitar pedals and compare the schematic to whatever schematic was the origin of the circuit. So when I traced the Rotobone, I cross-checked the schematic with the Bosstone and Mini Bone.

 

[Stickman393]

This. If it sounds right, then you probably traced it correctly. I also take advantage of the derivative nature of guitar pedals and compare the schematic to whatever schematic was the origin of the circuit. So when I traced the Rotobone, I cross-checked the schematic with the Bosstone and Mini Bone.

Worrrrddddd up! This one is a little strange. Not sure exactly what it's based on. Though I may just need to re-arrange and clean up my schematic in order to properly identify the patterns.

I've only traced a few simple circuits when I've been curious to find out how they were made. To me, if I build what I think I have traced and it sounds much the same I think I have achieved what I meant to. As long as I get a good result I'm happy! Usually I'm tracing something to modify it anyway... I don't think I've ever traced something just to copy it.

See, that's where you and I differ. I am *totally* doing this just to copy it.

Sorta. Mostly. But my current project is a simple little sweepable filter and gain stage from a rocktron "black cat moan" wah pedal. The "moan" circuit is relatively simple (five op amps, some doo dads, a couple of thingies). It piggybacks right on top of a standard, slightly modified crybaby circuit.

Kinda want to see what I can do with it. It's got a character that I'm intrigued by. It *seems* like it's a bit differently laid out than, say, the Parapedal. It might be It doesn't use an inductor: I know that much. Though I bought a Hiwatt wah recently that looks *damned* similar to the parapedal: that guy is one of the next on my list. I'm also planning on tracing out the first generation 535: that's mostly just gonna test my patience with tracing out NAND and JFET switching circuits.

Certainly doesn't look quite like a WH-10 single pot variant either. Or maybe it does. Gonna fuck around with it a bit tonight and try to figure it out.

I dunno. I'm not much for book learnin' unless I have hands on experience with stuff and can visualize the interconnected pieces while I read. Otherwise I just end up letting my eyes glaze over and get itchy.

 

[Feral Feline]

In a less flippant response, I will say that ...

"VERIFIED" ...

... means different things to different people.


To many of the Vero-Cowboys'n'gals, if the vero works at all, it is "verified".


To some, "verified" is a working circuit that sounds close to the original circuit, even if some of the values of components are not known outright but have been best-guessed at.


I've never understood these "verified"-mentalities when there is still questionable validity to types and values of components as well as often guessing at what the circuit paths are when based on a partial-trace from photos.


To me, "Verified" means a working reproduction of an entire known-circuit (whether on breadboard/perf/PCB and if must be, on vero), all parts are known and used (save for unobtanium such as SAD1024 chips in a flanger circuit) — and it has to SOUND the same (allowing for parts-tolerance differences).


Some things aren't/can't-be replicated, such as the code for FV-1 algorithms, or the code for Fairfield Shallow Water — but if it can come close I'm happy with that.

I know my Nobelium can't ever be a true replication of the Noble DI, due to Noble's use of a proprietary transformer — but if something sounds good to me then I am satisfied and don't need that last percentage of the puzzle.

In fact, hypocritically, I rarely care that something is NOT an EXACT replica. I generally want to start as close as possible to the original circuit-baseline and mod it from there.


VERIFIED circuits should behave like and sound like the original traced unit.


Lastly — I LOVE the BlackCat Moan !

 

[HamishR]

Oh I completely agree that VERIFIED should be exact. I never think of my traces as being "verified". I think of them as a useful starting point. And I don't trace many circuits because that can be really hard!

A while back with Chuck's help I traced the Animals Pedals Diamond Peak, designed by Skreddy. We had to guess a lot of values from other Skreddy designs - well, Chuck did. And once I had an idea of how it worked I wanted to add a bass pot. The Diamond Peak is already a fantastic overdrive but I wanted to be able to add some lows to work with a Strat and some of my amps, and maybe cut a little bass for use with a Les Paul and Marshall. Once Chuck showed me how to do this I dialled it in for my taste.

I don't see the original schematic as being sacred. Maybe sometimes the designer designs purely for his or her needs but often I suspect they are designing to appeal to as broad a base as possible, hence all the switches people like Barber and Wampler include. With the options I find that usually we quickly find the settings we prefer and stick to them. So I'll usually leave the options out with only my preferences left to simplify the circuit and prevent myself from hitting the wrong one. Wampler pedals can get a bit too bassy at times so I'm tighten them up, or BJF designs will use LEDs for clipping which I'll swap for something else.

This is why I like to BMO. (build my own)

 

[Passinwind]

A'ite. Question.

Let's say you've traced out a circuit. Like, you've got the board, you've peered at the traces for hours on end, used a meter to confirm continuity, and built a schematic from that board.

Whatcha all do to *verify* that your schematic is correct?

I put it in LTspice and see how I can improve it, of course. I've actually done this all of one time, as there were no build docs for that particular pedal at that time, and it was going to be a build for a friend that I didn't feel like doing my own design for.

 

[finebyfine]

I put it in LTspice and see how I can improve it, of course. I've actually done this all of one time, as there were no build docs for that particular pedal at that time, and it was going to be a build for a friend that I didn't feel like doing my own design for.

I’ve never traced a pedal but I’ve copied plenty from unverified schematics and this is what I’ve done. If you’re feeling extra anal you could compare the LTSpice simulation with an oscilloscope on the pedal too

 

[Passinwind]

I’ve never traced a pedal but I’ve copied plenty from unverified schematics and this is what I’ve done. If you’re feeling extra anal you could compare the LTSpice simulation with an oscilloscope on the pedal too

I do computer RTAs on anything EQ related as a matter or course, and typically scope anything and everything I work on right off the bat as well.

 

[finebyfine]

I do computer RTAs on anything EQ related as a matter or course, and typically scope anything and everything I work on right off the bat as well.

Sorry if I implied you didn’t, I wanted to phrase that for OP while building off your post.

What is RTA?

 

[Passinwind]

Sorry if I implied you didn’t, I wanted to phrase that for OP while building off your post.

What is RTA?

Real Time Analyzer. I highly recommend Room EQ Wizard, which is freeware. There are VST plugs that work OK too.

And not a hint of offense taken, I was just trying to flesh out your post!

So suppose we wanted to see for ourselves where the actual nominal flat setting on a G-K MB500 Fusion amp lies. We hook up the amp to our audio interface, using the EFX output to keep things relatively simple. Set all EQ knobs at noon, measure, then start tweaking. Voila, we get:




This was quite useful when I was revamping one of my DIY bass heads for a friend who owned it for while, I had him shoot me a pic of his control settings and changes treble EQ comonent5s until I got as close a possible to what he preferred. Some might call that ruining a perfectly good amp though...LOL!

 

[hamerfan]

Just a noob question: Could AI used to trace? If it can find cancer in shadowy pics….

 

[Nostradoomus]

AI can't even draw hands so probably not. Learn a skill.

 

[hamerfan]

AI is not good in creating something really creative or doing things that is not following regularities, but it can surely recognize patterns and convert them. I mean if it knows the color bands of resistors it can express the value in numbers and put it into a schematic. It would be time saver.
You still have to look it over and verify the schematic.
I am quite sure that Nux, Mooer and the other chinese brands do their clones that way.

 

[finebyfine]

Circuit board reverse engineering is a big industry with lots of water well treaded. I’m sure AI shit is being worked into it aspects of it but it’s an old enough industry to have existed without it.

Most Chinese pedal manufacturers have full fledged R&D teams that use existing pedal designs as reference just like anywhere else.

 

[JTEX]

I usually just input the schematic into a circuit simulator and see if it works. I might place virtual scopes/meters/spectrum analyzers/signal generators around the schematic and compare with what the physical board does. After I discovered circuit simulators I almost stopped breadboarding.

As much as possible, I break down a complex schematic in functional blocks and test/simulate them separately. Divide and conquer.