First post! Obsolete transistors & Parts?

[Jbassfunk75]

Hey everyone! I love this site, I've built a couple PCB fx but decided that it was about time! So I went over to Tayda and picked up some strip board. I thought I would start by building something that wasn't too difficult, just something like a boost or similar to get rolling with this process.

But what I didn't expect was how many (nearly 90% actually) of the builds on here required rare, no longer manufactured, obsolete, or downright impossible to find transistors, IC's, & diodes.. Some can technically be sourced from eBay and the like but the prices are outrageous not to mention that there's no way to know what you're getting with China flooding the market with such a massive amount of fakes..

I'm wondering what you guys do when you encounter a build with an obsolete part with no real 1:1 equivalent? Do you use something that's "close enough" even if it's not spec'd very close at all..? Like a 2n5457 for example what would you use? Maybe you're aware of a reputable source supplier?? Thanks

[Pavlos]

first of all welcome

and so starting last regarding 2N5457 (And for that matter most other of our commonly used JFETS) the through hole version (TO92 package) have been out of production for so long now that it is almost impossible to find anywhere that has anything like reliable spec let alone an affordable price. The good news is that the SMD versions (SOT23) are readily available, with reliable spec and at affordable prices, the only downside is that they are fiddly little buggers (Get your soldering skills up before you try them and be very patient) and you'll need daughterboards to use them in the layouts on here.

This is where I get both my SMD JFETS and the daughterboards
http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=1&products_id=286

Regarding obsolete transistors and diodes, I'm assuming you are refering to germanium? if so there is a whole thread dedicated to the subject
http://guitar-fx-layouts.42897.x6.nabble.com/Great-Jumpin-Germaniums-Ge-Diode-and-Transistor-Reviews-Discussion-tp13256.html
and if you read through the posts for similar layouts that use the same components you'll find a lot of more readily available workrounds that work really well such as Russian transistors and diodes.

http://alltransistors.com/mosfet/transistor.php?transistor=19202 is a good place to compare specs as well, important considerations for possible alternatives are the pin layout (CBE, EBC, BCE etc) and as long as that is compatable any transistor with a similar HFE should work. Again it's well worth reading through the posts to see what results others have found with different transistors.

diodes are (Especially if in groups of 2 or more) often used to create clipping / distortion and different types have different characters, some more aggressive, some smoother http://guitar-fx-layouts.42897.x6.nabble.com/3-options-clipping-switch-td37066.html#a37074 could be worth building to experiment with in future.

IC's are mostly easy to source, and in most cases the letters at the begining and end are not something you need to worry about too much. They refer to a manufacturer and usually part of the spec that isn't imprtant for the uses in gutar pedals (High thermal capability ect) so RC4558, JRC4558, JRC4558NM are all interchangeable. Also most DIL op amps have the same pin layout and are interchangeable, so you can usually use TL062, TL072, TL082, 4558 and many others and have a working circuit. There are a few IC's that are a bit more tricky though, CA3080 and LM308 spring to mind as they are long out of production and it's easy to get duds if you're not careful http://www.musikding.de/?lang=eng are reliable for both though.

http://guitar-fx-layouts.42897.x6.nabble.com/Reliable-and-Unreliable-Part-Sellers-Ebay-or-Webstore-tp38548.html is a good source of info on where to get parts, otherwise I'd thoroughly reccomend you to put your feet up with the drink of you choice and read, read, read through the posts, there is so much information there that is really helpful.

Oh and smart move to start small and simple, a lot easier to find and sort out any issues you might encounter, so LB1, one knob fuzz then work up to things like OD250 would probably be good, just keep taking little steps

[Jbassfunk75]

Thanks!!
While using smd's is a fantastic suggestion, I have to say I'm skeptical about how successful I'd be working with these.. I accidentally ordered an smd type TL072 awhile back and MAN is that thing small!! I'm also uncertain if it's even possible with my soldering station, which doesn't have smd type tips or hot air hookups. Maybe you could manage without them? Again I'm skeptical haha.

[balazs.bencs]

It takes some time and practice to be successful, but it is absolutely doable.

Soldering SMD transistors are not a hard thing to do, you can solder the legs one by one while holding them with a tweezer. ICs are much harder, but I recommend using flux on the legs. I did it several times when I put flux on the legs, and I just had to slide through on the legs with my soldering iron and everything got soldered correctly and neatly.

Here is a youtube clip on how to do it, I recommend checking it out: https://youtu.be/b9FC9fAlfQE?t=1161

[Pavlos]

I agree, it does take a bit of practice, and above all patience to solder SMD componenets. It is also a good idea to either pin the board down somehow or use 'helping hands' type of device to hold it steady
https://www.amazon.co.uk/Mercury-Helping-Hand-With-Magnifier/dp/B000L98020/ref=sr_1_3?keywords=helping+hands+vice&qid=1564147237&refinements=p_36%3A-500&rnid=193401031&s=officeproduct&sr=8-3

For the actual soldering I find that a dab of flux on either the board or underside of the component also helps keep the components it in place, then I transfer a relatively small amount of solder to the tip of the soldering iron which allows me to get about 3 or 4 joints done, then re-load and continue. I also find that having the hand holding the iron gently braced on the table also helps keep it nice and steady and allows me to be far more accurate

there is a clip on here about how to solder SMD as well
http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=1&products_id=286

The good news is that it's only really yhe JFET's that you'll need to use the SMD version, nearly all of the IC's and other components that are used in the layouts are relatively easy to find in normal through hole packages so you probably won't need to resort to the SMD verson for them.......unless of course you enjoy 'micro soldering'

[nocentelli]

Pavlos wrote

The good news is that it's only really the JFET's that you'll need to use the SMD version, nearly all of the IC's and other components that are used in the layouts are relatively easy to find in normal through hole packages so you probably won't need to resort to the SMD verson for them.

Some of the through-hole BJT transistors that used to be extremely common in DIY circuits are being phased out (I think 2N5089 for example), but unlike JFET's, alternative/equivalent transistors exist and are still in production that will do they job equally well.

[IvIark]

I find it really funny actually.  It doesn't seem that long ago that I started doing my first layouts and when I did I could buy 100 x through-hole J201s or 2N5457s for less than $10 from dpi4parts in the US.  All original Fairchild's as well.  Thank God I'm a hoarder

But yes SMD is the way to go. If you're struggling try flux and it becomes a lot easier, like this example

[Sensei Tim]

Semi-bad news:

Sot-23 2N5457 are EOL on mouser :(

[IvIark]

Maybe it's just the particular manufacturer?  I don't know but JFET transistors are never going to be obsolete from use in our lifetimes so hopefully the next generation of effects start to be based around a common JFET that's used extensively in other industries so the price and availability is never an issue.  There's no reason why these effects can't be built around something other than unobtainium.  It's just that a lot of the core designs were done a number of years ago when J201s and 2N5457s could be bought in their thousands for less than a penny a piece.  Hopefully some people start designing effects again some time soon instead of rehashing a Tubescreamer for the 20,000th time   There's probably more chance of something like that starting in places like this where people are more open to trying something new and sharing it.

One thing I will say though is that as far as DIY is concerned there's no reason why you can't continue making effects around the J201 or 2N5457 forever more.  If you use sockets you could share JFETs and just have them installed in the effects you're using at a particular time.  Not ideal maybe but most people will only use a few dirt effects in their chain simultaneously, so swapping components between effects is always an option at least.

[Sensei Tim]

I don't know - on another group there was a bit of a panic buy and some folks bought several thousand.

I mean, there are plenty of other alternatives - j202, j203, j113 (I think) and probably 100's of others.

people just don't want to sift through all of those data sheets to find something similar.

[Muadzin]

When I first started, late zero's I was using a lot of Millennium bypass switches, as those were cheaper to build back then then 3PDT's. And at the time the J-201 was the tranny of choice for the Millennium. And probably not because they were that good, or necessary, the BS-170 seems to be the tranny for that now, but because it was dirtcheap and available back then. I wish I had had the foresight to hoard a couple of thousand back then. But who in his right mind who is not called IvIark hoards that many on principle? But these days, hoarding any through hole transistor or IC still in production makes sense. As they're almost guaranteed to go out of production at some point.  

I pity the people who are currently coming into the hobby. There are way more vero layouts and PCB projects available to them when I did, and there is a lot more option in webstores selling electronics as well. But there is less stuff available as more and more is going out of production. And yes, there are still plenty of NOS parts available, but its getting to be a chore to order them. You used to be able to order everything from one place. Now you have to order most parts at webstore X, some rare parts at webstore Y and the unobtainium parts at webstore Z. The shipping costs alone for all those orders starts to become bigger then the parts costs themselves at times. And that's excluding the pain in the ass that is SMD. Which is still the best way to go for JFET's.