Drunk Beaver OverBooster (A Boss FA-1 Fet on crack)

[sharaynishi]

Hello, I've found this schematic posted by the man himself in his github page and was wondering if there is anyone on this planet who is interested in this pedal and would like to do the tedious job of making it into a (preferably) vero layout.

Here's the link to the schematic https://github.com/vitaliy-bobrov/boba-fet-amplifier/blob/main/images/schematic.png

[fx-fidden]

I'm working on it. Do you still need a veroboard layout?

[sharaynishi]

Sorry for the mega delayed response.

Yeah, that would be amazing!

[fx-fidden]

Clearly it's very similar to the Boss FA-1 with some mods.

I started from a verified layout of the BosS FA-1 and redrawn it.



The layout is NOT verified, so you could build and check it by yourself.

[sharaynishi]

Hello, it don't work, Sir.
Led's light up and all that jazz, but I'm getting no output at all.


Merry Xmas!

[fx-fidden]

Thanks for trying it.
While you check your board, I check the layout. We'll see if it can work.

[sharaynishi]

Alright. Just some pointers - i tried 4558, tl072 and 4580 ( I figured it wouldn't make a difference).

[fx-fidden]

Those IC should be ok.
I checked the layout, but I didn't find anything wrong, looking at the schematic.
But maybe I found what's wrong.
if you have the original Boss FA-1 transistor 2SK246-GR (or similar pinout DGS) this layout I guess it will work.
(https://1.bp.blogspot.com/-x98ZO-YMJ74/X7dZx78r0SI/AAAAAAAADlU/6_X8qzoY_R4cPft2lrZjHaLR97tFy-uaQCLcBGAsYHQ/s1062/Boss%2BFA1%2BFET%2BAmplifier.png)

Else you have to try to invert the pin S and G.



I hope that's it. You should try, at least to know if all the rest work.

Else...
Did you check everything in your build?
Maybe some pictures can help us to check it out together.
Check if wires are in the right spot, like the all the caps and resistors. If you have doubt about the the position on the board try to look at the schematic.
Count the cut tracks and check if the strip are really interrupted.
Check the orientation of the electrolytic caps and  the 1N5817 diodes.
Count the jumpers.
Tell us the IC and the transistor voltage.

Anyway, I could re-drawn the layout with the right pinout transistor, but maybe you need to build it again, because you could make your board some mess, if you decide to adjust it.

[Neil mcNasty]

I see one very obvious mistake; The JFet transistor has the wrong pinout configuration.
If you use sockets, you can bend the legs (add heat shrink to avoid contact between legs when bending them), but otherwise you'll have to resolder it.
You could also try to switch it with another JFet that has the DGS configuration as well (MPF102 is often used as alternative to 2N5457). That way you will not need to redo the layout, unless there are other errors discovered.
The circuit might not be too picky about which transistor you use, and part numbers are not that important as getting it up and running. Most part are inter-changable, and this specially goes for transistors. A lot of fun results can be discovered by doing stuff "wrong". (Devi Ever/Death By Audio/Dwarfcraft Devices are perfect examples)

On your layout: The JFet is confugured DGS (top to bottom) which is how MPF102's and SK30AY are configured. But this is not the case with 2N5457, which should be configured: DSG

This is the case for most JFet's and it is a good practice to always check JFet pinouts. They can be a pest and it is easy to forget to check, causing a lot of headache because you are looking for errors everywhere else (like I have done a lot)

It is one of the most common error in layouts containing JFet's, and I've noticed that this error is circulating frequently on the newer layouts posted here recently.
It it is a subject worth some attention I guess, since there are probably a lot of new people here that could benefit with a little input and engagement from the more experienced users.

Some pedal builders shun JFet's like the plague due to the Bias issue and poor noise-floor (worst in Mosfet) alongside the variations in pin configuration. But who the hell cares about a poor noise-floor in a distortion pedal? That is often what we want! That is why I love Germanium! Crappy Quality making wonderful sound!

Anyway... Just wanted to inform you about the error, and add some information that I hope someone will find usefull...
Great to see increased activity lately!
Keep on chucking out those layouts! It is highly appreciated!
Cheers!

[fx-fidden]

Thank you. This mistake has been noticed, indeed.

Some jfet image/layout/pinout confused me while I drawn layouts, especially my first times. Then I learnt it. This should be one of those first layouts.