Replacement for J201?

[Guitarist335]

I am building a circuit that requires a J201 transistor. It is a buffer circuit for an overdrive.

I don't have a J201. Here is what I have:

BC327, BC337, BC517, BC547, BC548, BC549, BC 550, BC 556, BC 557, BC 558

S8050, S8550, S9012, S9013, S9014, 2N3904, 2N3906, C1815, A1015, 13001

Does anyone know if any of the above can be used in place of the J201?

Thank-you

[duck_arse]

none on your list are jfets. the j201 is a jfet, so none of your parts are direct replacements. if you head over to AMZ and look for the pages on buffers, you'll see how a bjt can be used as a buffer. your parts are all bjt's, I think.

[Vivek]

If you post your schematic,

The good folk here might be able to propose a BJT based buffer with somewhat similar characteristics as the J201 FET one

[Mark Hammer]

There is nothing special about a J201, when used as a buffer.  If you have access to other garden variety JFETs, like 2N5457 or 58, MPF102, 2SK30, etc., any of those can sub for a J201.  Just be VERY careful about the pinouts, since they can vary depending not only on part number, but manufacturer.  Always look for a pinout diagram for the specific FET and manufacturer.

But yes, BJT buffers can work just fine, and Jack has many good suggestions at his AMZ site on the Lab NOtebook pages.

[Steben]

As a buffer, BJT can be sufficient.
In theory, a BJT design in a gain stage even can give the same harmonic content. And low gain in input stages can have high input impedance again etc etc etc.
But a BJT will never clip as a jFET.

[antonis]

If the overdrive circuit is based on a single op-amp, you can implement a dual one for buffer use..
(same for odd number op-amps..)

[Guitarist335]

Thank-you for all the advice and info. I have bookmarked this page and plan to review it in greater depth.

[DIY Bass]

The J201 is also pretty easy to find still as a surface mount component.  It is possible to find PCBs that you can solder the surface mount one to and adapt it to go into a through hole board.  I am sure I have even seen some people selling them with the J201 pre-soldered if you don't want to try soldering surface mount.

[EBK]

It is possible to find PCBs that you can solder the surface mount one to and adapt it to go into a through hole board. 

I posted a tutorial for making a cheap and relatively simple adapter board from stripboard as an alternative.

[anotherjim]

If the JFET drain resistance is fixed, then the bias point will vary by device and clipping symmetry changed. Different parts can sound different. Maybe always make this resistor variable?
If the drain resistance is variable, then you may bias consistently, but the output impedance is changeable and that alters the high pass frequency of the following coupling cap. Different parts can sound different. Maybe pick a generous size coupling cap and drive any tone stack with a source-follower, just as some tube amps used a cathode-follower?