BLM Fuzz: stripboard layout assistance

[mdcmdcmdc]

Hi folks

I'm interested in building up one of Kurt Ballou's tone bender variants, the BLM fuzz. The PCB is unavailable, but the schematic is included in the build doc here.

So, I thought this might be a nice opportunity to try DIYLC for the first time and see if I can make this work. I spent a bit of time working through it this eve, and it'd would be much obliged if you keen-eyed humans might take a look at this attempt and point out what I assume are a laundry list of mistakes.

Schematic:


Layout:
[EDIT - updated layouts further down]

Thanks in advance, the help is greatly appreciated.

(EDIT - caught a misplaced jumper and corrected it)

[duck_arse]

gah! vero read!

your transistor outline is correct for BC series transistors. 2N series would face the other way, which you know from your datasheets, close at hand ......

never mind all that - you need to rework the bottom left corner - D2 kathode goes to that electro and nowhere else. and the external 9V goes to an unprotected circuit.


8999

[mdcmdcmdc]

Oof, that's what you get for tryining to tack on the power supply last minute I guess. TY, correction coming.

[cab42]

Isn't there something wrong near the input?

C2 (1n) should be connected to R1, R2, C1,  Range 3 and Q1 B. But as far as I can see its connected to R2, C1 and Q1 C (and other stuff)

Range 3, R1 Q1 B are connected together but missing a link to C2. It looks like the jumper K8-F8 is on the wrong side of the trace cut F5.

This is my 666th post, so I might be wrong 

However if it is correct I think I have idea on how to rearrange.

[mdcmdcmdc]

I went through it again so here's another attempt (gained a column, lost a row):



This is a fun puzzle, but there's a lot of looping around in the schematic which is messing with my brain a bit.

[mdcmdcmdc]

I think a 5817 will actually fit fine across 3 rows so...

[cab42]

I think you can compact it a bit further.

You can ditch column 21:
    - Move vol 3 to K1
    - place a trace cut in K9
    - move the 1u from K21-I21 to K8-K10

    I know someone will object having "horizontal" components in one row, but that's mostly for aesthetic reasons.


Same with column 20:
    - Move the 2.2n from B19-D19 to B18-D18
    - Move to 10K from D20-G20 to D19-D19

Lastly column 2 and 6:
    - Move trace cut E4 to E9 (under the resistor)
    - Move the 10M from F2-I2 to E8-A8
    - Move the 47uF from C4-A4 to C3-A3
    - Move D1 from E2-C2 to E4-C4
    - Remove the jumper and column 6

That's four columns less 

[mdcmdcmdc]

Aside from squishing it in, does the layout look correct-ish? I definitely started to get lost in the weeds when I got to Q3.

[mdcmdcmdc]

...and obviously, thanks so much for the assist!



I left one extra column next to the 220n cap as my own low key ocd goes nuts when oversized caps are jammed on top of resistors and go all crooked. A multilayer ceramic would probably make it a non-issue, but I think I only have greenies or boxes around.

[mdcmdcmdc]

Oops, I left a vestigial cut at I-18.

[cab42]

I left one extra column next to the 220n cap as my own low key ocd goes nuts when oversized caps are jammed on top of resistors and go all crooked. A multilayer ceramic would probably make it a non-issue, but I think I only have greenies or boxes around.

That's actually a good point. When you try to optimize something you often get to a point where the optimizations a) causes inconveniences in other places and/or b) really doesn't make any practical difference.

But a multilayer ceramic would do wonders. Then you could also get rid of the jumber H15-J15 and maybe even save a column more. I have some I got in a grab bag of assorted components years ago. They are the size of a rice grain. Very convenient.

I checked the layout before you made the last changes from my suggestions, so if the new changes hasn't messed anything up, I think it is ok.

s is a fun puzzle, but there's a lot of looping around in the schematic which is messing with my brain a bit.

Yeah, vero's are fun!

[andy-h-h]

Hello

Personally, I think a logical layout is more important than a small one.  It's still 22 across, so there's no great need to make it any smaller.  More space for components reduces the likelihood of solder bridges, looks neater and gives you more room to work (IMO)

Also I think there may be an issue with the schematic - as this is a silicon npn variation of a Tone Bender MKIII.  The 10uf capacitor would normally have the negative side connecting to ground.   

[mdcmdcmdc]

Also I think there may be an issue with the schematic - as this is a silicon npn variation of a Tone Bender MKIII.  The 10uf capacitor would normally have the negative side connecting to ground.   

Thanks for that catch—that's odd for sure. Unfortunately there's no trace-side photo of the board to check against, just the top:


The two electrolytics seem to be oriented opposite from one another but probably not safe to infer anything from that.

[duck_arse]

..... my own low key ocd goes nuts .....

we use OCD as the force around here, keeps things right-thinking. a very useful tool indeed, Luke.

if I might make a few observations - your transistors are now showing as un-part-numbered. if using 2Nxxxx, they are outlined backwards. your 10uF cap is backwards. to me, your poly cap connections are ambiguous. if you reduce the components "Alpha" setting, we can then see if the leads are 3 holes or 4 holes. personally, I'd put a cut in that long long J track, as it's connecting to the transistor base, which doesn't need an aerial. AND - there is certainly no restrictions on horizontal components - I see lots of unused space and uncovered holes that makes my mouse finger itch.

[mdcmdcmdc]

Re: the backwards 10uF, I haven't breadboard'd the circuit yet to see if it'll actually work with the cap per-schematic but it definitely is backwards from a normal NPN TBMKIII. I need to grab some 10M resistors...

And to ease any collective horizontal-cap-induced eye twitching, I think I can just remove the cut at K7 and move the 1u to K4-I4 with Vol 3 connecting at I1. And ty for the suggestion of adding a cut at J12—I wouldn't have thought of that.

[mdcmdcmdc]

Confirmed that the backwards 10u is indeed a mistake on the schematic so flipped it on the layout.
Thanks again, sincerely, to everyone who chimed in and helped out with this—very satisfying to take some first steps in learning a new skill.

[mdcmdcmdc]

Hi - just wanted to bump this thread to mention that I found some time to build this up and it seems to work more than it doesn't work, so thanks again for the help checking over the layout.

There are a few odd things happening, but without a pedal built off of the PCB to compare I can't tell if they're features or bugs. For one, it has monstrous amounts of output—unity is at about 9:00. Turning the fuzz down to zero cuts the volume completely. There's also some odd sputtering and gating going on but I haven't had a chance to play with different transistors at all. It's currently built up with 2 metal can 2N2222a and a 2N5088 that I pulled at random.

That said, it's passing signal, it gets fuzzed out as heck, and the range knob does seem to do a lot (sub'd a B500K for the C500K which I did not have).

I'd call it verified-ish?

[duck_arse]

according to the circuit dia shown up there ^, the fuzz pot goes to zero. you could put a stop resistor under the pot for minimum. as for sputter, measure and post your transistor voltages, and the smarter blokes will tell if they look right or not.

of course, if you were to post photos of your build, solders, wirings, we'd all have a look to see if there were any errors you'd missed .........

[cab42]

according to the circuit dia shown up there ^, the fuzz pot goes to zero. you could put a stop resistor under the pot for minimum. as for sputter, measure and post your transistor voltages, and the smarter blokes will tell if they look right or not.

of course, if you were to post photos of your build, solders, wirings, we'd all have a look to see if there were any errors you'd missed .........

I was just writing pretty much the same thing...

It was the first time I was looking at the schematic with the purpose of not just checking the layout. At first glance I thought it was a Tonebender variant, but there's a couple of things that are different as far as I see. The collectors of the two first resistor are connected, instead of each having a resistor to v+, the base of q2 is fed from the emitter of q1, and then the fuzz pot.

I'm not knowledgeable enough to see the significance of this, just an observation.

[duck_arse]

looks like a Darlington pair? with base pull-down, sometimes seen.