J201 JFET question

[wretched]

I am getting together my parts for a Tweedy Bird and I need 6 of them to be pretty much the same. I am wondering how consistent they are and how many I should buy. I was going to get them from tayda

[haveyouseenhim]

The ones I got from tayda varied wildly. I would recommend buying some smd J201s from chromspere's store. There is a little adapter board you can etch or ask him if he has any.

[midwayfair]

>I was going to get them from tayda

I'll just go ahead and recommend against that. For one thing, Tayda's J201s aren't any cheaper than, say, Smallbear, and Smallbear's are known genuine Fairchild transistors.

You are going to need a PILE of them to make several close matches. At least 20. The leftovers are useful in other effects, so it's not wasted, even though it seems a bit expensive now. FETs are like delicate little snowflakes and they all want to be different from each other, so figure it you're just trying to match drain voltages within .05V, and the range can be over 1V on various pieces, you can see that there is a lot of room for it to be "wrong." Fortunately there is a bell curve near the center that will get you pretty close on several. But you still need a lot of transistors.

[wretched]

From Smallbear with shipping for 25 it is about $22US.

I ended up ordering them, now just keep my fingers crossed that I find at least 5 or 6 close matched.

[jubal81]

You could always offer a bounty to someone on the board to send you a matched set. My stockpiles are pretty depleted at the moment or I'd offer.

[wretched]

I was going to, but I see a few other projects that need j201s so I figure I should start a pile of my own.

[wretched]

I ended up getting the ones from Small bear at the same time as the tayda ones. Small bear is on the left and the tayda one is in the right. You can see the differences

[pickdropper]

I ended up getting the ones from Small bear at the same time as the tayda ones. Small bear is on the left and the tayda one is in the right. You can see the differences

The one on the left looks real to me.  It is *possible* that the one on the right is real but came from a different fab. 

[juansolo]

Tayda J201s aren't. Stick with Smallbear or make your own (as we have to do now).

[playpunk]

Tayda J201s aren't. Stick with Smallbear or make your own (as we have to do now).

how do you make your own J201?

[rullywowr]

Chromosphere has a great video on it. Basically j201 are available in smd. You solder the smd j201 to a breakout board (mini PCB) and then it functions just like a through hole j201.

[kothoma]

http://www.madbeanpedals.com/forum/index.php?topic=11732.0
http://www.madbeanpedals.com/forum/index.php?topic=8802.msg95978#msg95978

[kothoma]

also search for "SOT23 to SIP3 adapter"

[chromesphere]

here's a link to the video, pcb layout, and product listing for the smd j201 (mmbfj201) conversion for anyone playing along at home:

http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=6&products_id=52

[wretched]

My SMD soldering tip is to use some tape to hold the SMD in place for the first solder spot. Seems obvious but I overlooked it for so long.