Surface mount J201 adapter wiring

[Mike McLane]

I have surface mount J201's mounted on PPCB's adapter pcb. The adapter pcb is labeled D--S--G, but the pedal pcb (Son of Ben) is mfg for thru-hole and according to the spec sheet the scheme for thru-hole units is G--D--S. Further, the spec sheet indicates that SMT's conform to S (front left)--G (back ctr)--D (front right), but the tracings on the adapter pcb seem to have the Drain and Source bassakwards. Can anyone provide any help?

 

[Feral Feline]

Are you sure you're looking at the datasheet correctly?
Perhaps the view on the datasheet is looking at the underbelly of the J201, in which case once attached to the adapter-board it is oriented correctly.

You may have to twist the legs from the adapter board to the PCB's pads.
People do it all the time with through-hole, I see no reason not to do it here.

EDIT:
You must have an old board, the build doc I have shows SMD pads on the PCB. At any rate, check the pads you're connecting to with your DMM and make sure they in turn match where the pads lead to on the schematic.

 

[Robert]

I'm not sure what datasheet you're looking at, but the SOT23 adapter PCBs are a direct fit for the Son of Ben (and any other PCB here that utilizes the J201).

 

[finebyfine]

The TO-92 pinout in the OP drawing is wrong - there's some weird datasheets for j201 floating around online. The pinout is (flat side facing towards you) Drain, Source, Gate - the same order as on the smd adapter. The SMD boards map the mmbfj201 to the TO-92 pinout.

 

[Robert]

Ahh, InterFET maybe? I don't know what's up with that.

The pinouts / patterns for the PCBs here are designed for the pinout shown in the Fairchild / ON datasheet.

https://media.digikey.com/pdf/Data%20Sheets/Fairchild%20PDFs/J201-02,%20MMBFJ201-203.pdf

 

[benny_profane]

Can you link the data sheet you’re looking at? Also, double check the traces you’re seeing on the breakout board with the continuity setting on your DMM.

The source/drain on the j201 is practically interchangeable anyway for low-frequency (i.e., audio) applications. As long as the gate is correct, you’re fine.

 

[Robert]

This is probably the datasheet @Mike McLane is referring to: https://www.mouser.com/datasheet/2/676/jfet-j201-j202-interfet.r00-1649170.pdf

 

[benny_profane]

This is probably the datasheet @Mike McLane is referring to: https://www.mouser.com/datasheet/2/676/jfet-j201-j202-interfet.r00-1649170.pdf

Those are all mixed up. Why reinvent pinouts for legacy parts?

 

[Mike McLane]

YES! That's the spec sheet! And it does indicate that the view is from the bottom. Then we're good to go and the adapter pcb is just a straight plug-in as Mr PPCB indicates. Thx everybody!