# Correct orientation of JFET in Six String Stinger



## claudio (Apr 11, 2022)

It's the first time I make a build of something with these kind of transistors (gotten from Musikding.de).
Not sure how to orient them, can somebody please advise?

Should the face of the JFET, that is now facing up, point towards the power or the footswitch?


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## thesmokingman (Apr 11, 2022)

when in doubt, break out the continuity tester and correlate the pads on the pcb with the pads on the jfet breakout boards. and if you're contemplating replying that you don't have a continuity tester or don't know how to use one then you should probably fix that rather than waste your time and mine.


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## swelchy (Apr 11, 2022)




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## swelchy (Apr 11, 2022)

your j201 pcb is laid out in the correct order that a j201 would be... In the future you can look up the spec sheet for a transistor to see it's pinout in relation to the flatspot on the tranny...


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## bhcarpenter (Apr 11, 2022)

@thesmokingman’s suggestion is a good one too, although phrased a bit surlier than necessary 😉.

 Pretty much any DMM will do for continuity testing. If it doesn’t have a dedicated continuity mode, set it to measure resistance. Pads that are connected should read close to 0 ohms.


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## thesmokingman (Apr 11, 2022)

oh it's necessary ... go count the "passes signal in bypass" troubleshooting threads and get back to me


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## claudio (Apr 12, 2022)

https://www.mouser.de/datasheet/2/308/1/MMBFJ202_D-2316065.pdf

Looking at the sheet it actually looks like the transistor is tagged wrongly. D should be at the right and S at the left (when the pad side with the transistor is facing up). I checked with the multimeter, and the D on the pad has continuity with the D at the transistor, so we should consider that the D and S at the pad are also inverted. The question is what are the D and S at the PCB, so i can install it inverted.

Considering the PCB 's drawing seems to imply it wants the flat side of the transistor facing the footswitch, and in that case D would be at the left handside, I'd conclude I have to actually invert the pad. Am I wrong?


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## claudio (Apr 12, 2022)

Curiously, https://forum.pedalpcb.com/threads/six-string-stinger.7608/ also shows pads with reversed D and S on the pad.


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## swelchy (Apr 12, 2022)

Your overthinking  it.... look at the picture.. the legs are numbered in relation to the drawn schematic.. Your smd pcb is layed out in the same order a j201 is...


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## ICTRock (Apr 13, 2022)

it would also be helpful to know your smd package pinouts, js


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## claudio (Apr 14, 2022)

ICTRock said:


> it would also be helpful to know your smd package pinouts, js


what do you mean? i check the continuity between the transistors and the smd pins.


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## music6000 (Apr 14, 2022)

This is how they need to be fitted but standing up! :


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## ICTRock (Apr 14, 2022)

claudio said:


> what do you mean? i check the continuity between the transistors and the smd pins.


let's take the opportunity to expand your ability to help yourself. product datasheets. http://www.experimentalistsanonymous.com/diy/Datasheets/J201.pdf
This includes pinouts for both package types. Also, those electrical characteristics further down the datasheet become important not only in circuit design but, more relevant around these parts, parts substitution.


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## ICTRock (Apr 14, 2022)

music6000 said:


> This only leads to more confusion as only *Interfet* reversed the Source & Drain on their 201 datasheet!!!


if I can't introduce chaos then what's the point of all this?
I changed the link for the paint by numbers crowd


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## jwyles90 (Apr 14, 2022)

ICTRock said:


> if I can't introduce chaos then what's the point of all this?
> I changed the link for the paint by numbers crowd


Building pedals has quite the steep learning curve. "Introducing chaos" for someone who's just trying to ask a question doesn't feel all that helpful


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## ICTRock (Apr 14, 2022)

jwyles90 said:


> Building pedals has quite the steep learning curve. "Introducing chaos" for someone who's just trying to ask a question doesn't feel all that helpful


would you like a hug?


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## music6000 (Apr 14, 2022)

jwyles90 said:


> Building pedals has quite the steep learning curve. "Introducing chaos" for someone who's just trying to ask a question doesn't feel all that helpful


It Was a joke, no harm intended by* ICTRock*!


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## jwyles90 (Apr 14, 2022)

music6000 said:


> It Was a joke, no harm intended by* ICTRock*!


Well shoot, I guess I do need a hug then.


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## music6000 (Apr 14, 2022)

jwyles90 said:


> Well shoot, I guess I do need a hug then.


I'm curious where *claudio *has gone????


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## jwyles90 (Apr 14, 2022)

music6000 said:


> I'm curious where *claudio *has gone????


He fell down the pinout rabbit hole


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## claudio (Apr 15, 2022)

ICTRock said:


> let's take the opportunity to expand your ability to help yourself. product datasheets. http://www.experimentalistsanonymous.com/diy/Datasheets/J201.pdf
> This includes pinouts for both package types. Also, those electrical characteristics further down the datasheet become important not only in circuit design but, more relevant around these parts, parts substitution.


Oh, that explains it. I did post about the datasheet, which I did look at (see my comment #7) which suggested they were inverted. But I guess it was the *wrong* datasheet, because with the one you link to it all makes sense. Thanks folks!


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## Chuck D. Bones (Apr 16, 2022)

It's all a bit silly because D & S are interchangeable unless you're building RF circuits (which we aren't).


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## fig (Apr 20, 2022)

Chuck D. Bones said:


> It's all a bit silly because D & S are interchangeable unless you're building RF circuits (which we aren't).


That little factoid has come in handy breadboarding a few times.


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