Hi, I'm trying to build the mark IV from http://sabrotone.com/ .
I already built it on breadboard with 2n5457, and it sounded pretty good.
But the original shematic is with j201, and I heard it should even have higher gain as 2n5457.
Since I'm trying to get the closest sound as possible to the j201, and they are not easy to find in Germany, and quite expensive, what would be the best substitutes?
You could get the SMD version of the J201, and some of these tiny conversion PCBs ... Musikding has them. You might even have a better chance that they'll be 'in spec' than with through-hole versions.
Quote from: WormBoy on April 03, 2020, 10:18:30 AM
You could get the SMD version of the J201, and some of these tiny conversion PCBs ... Musikding has them. You might even have a better chance that they'll be 'in spec' than with through-hole versions.
+1. The SMD version is called MMBFJ201. Mouser has them for 0,32e + VAT in single quantities and the price goes down a lot if you buy more. Looks like they have plenty in stock at the moment (hasn't always been the case). SOT-23 is not something to be afraid of, it's tiny, but nothing like a 0402 resistor.
Yes, I have Seen lots of People doing it, although I'm not the soldering pro, so I doubt to be able to solder such tiny things.
That's basically the problem, and the reason cause I exclude the smd j201.
If someone would sell them already soldered, it would be fine, but I couldn't find any of them.
Does really not exist a transistor, that could replace the j 201?
Thanks anyway
Quote from: MadMilo666 on April 04, 2020, 01:29:46 AM
Yes, I have Seen lots of People doing it, although I'm not the soldering pro, so I doubt to be able to solder such tiny things.
That's basically the problem, and the reason cause I exclude the smd j201.
If someone would sell them already soldered, it would be fine, but I couldn't find any of them.
Does really not exist a transistor, that could replace the j 201?
Thanks anyway
I was soldering some j201s on adapters today, with a regular soldering iron. It's a bit tricky, but it's manageable.
I also managed with a normal iron to solder some of them, it's a bit tricky but doable. It would be better to use solder paste, but flux with normal tin will work just fine.
I've seen the J113 mentioned as substitutes, but a quick look at the datasheet suggests otherwise. I have some of them, but never tried to swap them with J201.
All in all, considered the variation of characteristics among jfets, probably you should just get a bunch of other transistors and test them. You should do it anyhow with the J201s. Once I needed 3 of them, bought 10 and they were all completely out of specs. I had to order ten more to find 5 or 6 acceptable.
That's why in my orange MkII build I used the smd version, which is a lot cheaper and has a smaller variation in specs.
+1. The difference in quality and consistency is crazy. It's what tipped SMD in for me, figuring I'd never be able to solder those tiny parts. You get creative with tape and/or tweezers as needed.
i use these for smd.
https://oshpark.com/shared_projects/7TAIpS4u
its easy to solder in. just use some blue tack on one side and stick it in the rigth position, solder one side , remove blue tack and solder the other side !
Quote from: gordo on April 04, 2020, 05:12:29 AM
+1. The difference in quality and consistency is crazy. It's what tipped SMD in for me, figuring I'd never be able to solder those tiny parts. You get creative with tape and/or tweezers as needed.
++! It isn't difficult, it's just tedious. Go for it.
Quote from: MadMilo666 on April 03, 2020, 10:03:02 AM
I already built it on breadboard with 2n5457, and it sounded pretty good.
You've already found your best substitute for the J201, (which 2N5457s are getting hard to come by as well). "Higher gain" components does not always translate to "louder" and "better". You'll most likely just add hiss and noise by using J201s. Stick with the 2N5457s. Soon you won't be able to get any of those either.
Quote from: jimilee on April 04, 2020, 07:56:34 AM
++! It isn't difficult, it's just tedious. Go for it.
Which is probably exactly why the OP won't find many who will sell him their tedious work. As for the OP, just do it. Yeah, it's scary, but until you do it yourself it will always be scary. And buying presoldered SMD J201's is probably just as expensive as buying the old through holes somewhere online. Although chances are you will most likely get ripped off with fakes. And if you don't you need a LOT to sort them out to get matching pairs. If you need to buy like a 100+ lot of through hole J201's to build a DIY JFET overdrive you've reached the pricepoint where you can almost buy the real overdrive you're trying to clone.
The way I did my soldering was to apply some solder to one of the three pads on the board, then take the SMD transistor with a tweezer, apply the solder iron to the blob of solder tin on the board, heated it up until it was liquid again and shove the transistor in it. Which sounds a whole lot more brute force and stupid then it actually was. The thing being that if the transistor was fixed to the board with one tiny blob to one pad it was much easier to add solder to the other pads and solder it in place. And afterwards I would check every conversion board with a multimeter to make sure there was continuity where it was supposed to be and no continuity where it shouldn't. Tedious work, it would probably take me a whole evening to solder 25 SMD transistors in place. Which is exactly why I won't sell you my hard work to begin with. ;D But it is a skill set you need to develop if you want to continue with this hobby as more and more through hole transistors and IC's go out of production.
Thanks a lot to all of you
For future seekers, pedalpcb has presoldered smd j201s for $2
Lectric-fx also has them for $1.40.
for the coffee drinkers with less than perfect eyesight :D
https://www.jedspeds.co.uk/product-page/jed-fet-j201-smd-to-to92-jfet
I dab solder on a pad, position the jfet and touch the solder blob and push the jfet in with a pair of tweezers, iirc. Then it's just a case of touching the other pads with a bit of solder to finish up as it's now held in place.