Bsiab Transistors

[POTL]

Hello
I want to try out some of the effects of JHS, Wampler, Catelinbread and other amp in a box builders.

But I ran into a problem in my country there is a great deficiency of the popular in such schemes transistors, especially J201 and 2N5457, the next replacement for the second 2N5952 and 2N5485 as Has no in TO92 housings can I find these transistors in smd packages, but have no experience soldering of small components.
What can you recommend to replace the in TO92 cases that tested and will work exactly?

[POTL]

What about BF245C?

[POTL]

I can choose from the following options:
BF245C
J112
J113

there are other options, but they cost almost a dollar apiece:
2SK170
2SK117
2SK246(Y)

[whoisalhedges]

You're probably not getting answers yet because this question has been asked many times (and will continue to be).

JFETs are funny things. They have a wide tolerance of operating parameters, and a lot of times two JFETs of the same designation will be more different than two of completely different types. That's just a wordy way of saying that for a 9v distortion pedal, just about any N-channel JFET will "work."

Will it sound good? Well, that's kind of up to your ears. All those different parameters you'll see in FET datasheets, Idss, Vgs, whatever, will affect the effect - more or less gain most importantly for a drive pedal. A lot of these DIY schematics call for J201s because they're cheap and available (at least in the US), and most of them have operating parameters that end up with them sounding good in gain stages.

Out of the ones you mentioned, the J112/113 and BF245C - they're all N-channel JFETs, they'll all work more or less in the circuit. From a quick glance at the datasheet (I am NOT an electrical engineer, nor am I even a talented amateur when it comes to the engineering/maths side of things), the 245 looks like an interesting sub - though it looks like it's got significantly more current draw, so you might use up batteries more quickly, and/or may need to adjust the bias resistors....

You really should get a couple of each available FET and breadboard it first. If you don't have a breadboard (why???) at least solder in SOCKETS so you can try different FETs in the circuit. When breadboarding, substitute trimpots for the bias resistors, and then take a resistance reading with your DMM so you know what is the "correct" resistance for the sound you want; then you can sub in fixed resistors of those values when you solder up the final circuit.

JFETs are, at the same time, really easy to work with and a huge pain in the neck. Best of luck.

[anotherjim]

The smd versions like MMBFJ201, if they are easier for you to get, might be better for you in the long run. They're easier than you might think to solder on a piece of perfboard which can be given legs - or if the project is on perf, then directly on the board.

[amz-fx]

What about BF245C?

BF245C should work okay but the pin configuration may be different than on the J201 or 2N5457, so check it carefully.

regards, Jack

[karis12]

I know it's not my thread, but: what's your opinion on using 2N5952 FETs for the Fetzer valve circuit? Tolerances are all over the place, but I did find a couple that had higher gain potential than even a J201, at the expense of input headroom.

[PRR]

> 245 looks like an interesting sub - though it looks like it's got significantly more current draw

In most of our circuits, "current draw" is more about the resistors.

If we have a 10K Drain resistor, we can NOT flow even 0.9mA out of a 9V battery, even if we stick a 25mA-max part in there. This may be about double the draw of a "right" part in a happy circuit. So a hit on battery life, but not huge, and usually not as bad as my poor-working example.

You are correct that that 25mA part may tend to suck 0.8mA, slam itself to almost-no volts D-S, and work poorly, without bias resistor changes.