Popular Transistors

[Phend]

What are some of the most popular transistors and why.
I see 3904 and 3565 often.
Maybe there is no such thing as popular.?

[duck_arse]

BC548. it was the industry standard here before we opened to the world. and then stopped manufacturing. it's the most ordinary transistor in the world.

[ElectricDruid]

BC548. it was the industry standard here before we opened to the world. and then stopped manufacturing. it's the most ordinary transistor in the world.

Yeah, I might have said BC547, but they're basically the same thing. All part of the BC108 family, which goes back a good way now.

https://en.wikipedia.org/wiki/BC108_family

For my own designs I got tired of the different pinout of BC547/557 NPN/PNP versus 2N3904/3906 so I decided I'd just pick one pair and always use those. As it happened I chose 2N3904/3906, but it could equally well have been the other way around. For many/most purposes you just need a "jellybean" part and any typical thing will do. For the few situations where that isn't good enough, you can choose something specific.

As to why these parts became popular, I'd say it's a combination of things. They start off being slightly cheaper than some other things, and that makes them more popular and common. Then they start being the go-to part in magazine articles and so on (I think the first transistor I ever saw was probably a tin-can BC108) and that makes them still more popular. More sales means more production and they get cheaper and cheaper, until they're basically the de-facto choice whenever you need something basic. The only reason there's 2N3904 and BC54x is because the Japanese, Europeans, and Americans don't coordinate!

[Baran Ismen]

On a closing shop, I've found some of the below at a cheap price, which I am considering buying but I'm not sure if I can use them anywhere.

2n5551
2n5401
BC550
BC560

Also these are quite common and present on nearly any common circuit;

2SK30A-J113
2N5087-88-89
2N5457-58-59
MPSA13
2N2218
2N2222

[antonis]

The only reason there's 2N3904 and BC54x is because the Japanese, Europeans, and Americans don't coordinate!

You disregard A, B & C suffixes for BC54X, Tom..  

[ElectricDruid]

The only reason there's 2N3904 and BC54x is because the Japanese, Europeans, and Americans don't coordinate!

You disregard A, B & C suffixes for BC54X, Tom..  

Well then, *there's* a reason to use 2N3904 instead - you don't have to decide whether you need 546, 547, 548 549, or 550 and then decide whether you need the A, B, or C version! Much simpler!

On a closing shop, I've found some of the below at a cheap price, which I am considering buying but I'm not sure if I can use them anywhere.

BC550/560 would be a handy NPN/PNP pair to have around, I'd have thought. More than good enough for all basic transistor jobs.

[marcelomd]

Hi,

2N700x is a very common N channel mosfet. Used as gain stage (saturate or not) and as diode clipper. It's the BC54x of the N channel MOSFETs. BS170 is more or less the same with different pinout. BS250 is its P channel brother.

LND150 is a depletion mode N channel. People pair it with tubes all the time. Saw it in a few pedals too.

J201, a JFET, is used in several overdrive/distortion pedals as saturated gain stage.

J175, another JFET, is used as a signal switch in a lot of pedals and amps.

[Lino22]

BC550, a nice, round number. IT has A, B and C instances. If you are not sure, get C.

[antonis]

BC550, a nice, round number. IT has A, B and C instances. If you are not sure, get C.

Not sure for what..??

[Phend]

Sounds, no pun, like almost any to92 transistor will work in most effects.
Some may need to be matched like phase shifter,
Some may want higher hfe or lower.
But in general, any "general purpose" transistor will work.
If so, what is the "sound" difference between 2222 and 3409, with the same hfe?

[antonis]

In a carefully(*) designed ciruit, none..!!

(*)counterbalancing for possible Early voltage, Base spreading resistance, Forward transition time, B-C / B-E built-in potentials and other nasty parameter inequalities..

[R.G.]

Sounds, no pun, like almost any to92 transistor will work in most effects.

See Keen's Second Law: When in doubt, whip in a 2N5088.

In the USA, it's generally easier to get 2N... transistors than BC.. or 2S... devices; or at least it was up until a few years ago.
I like the 5088 as it's also a quite low noise device. 2N3904 will work nearly anywhere, as will most BC5xx and so on. So yes - If you can't get the transistor you love, love the transistor you're with.

The phenomena of nearly-any-transistor-will-do is recent (and the foundation of the NTE business) in that semiconductor processing has gotten really, really good. Different type numbers were a result of wide, wide variation in the results of semiconductor fabrication in the 1960s; they had to cook a batch, test them, and then sell the results sorted into different "part numbers" based on the tests. Also, transistor design was poorer half a century ago. Designers would rely on specific transistor gains and other properties to get a circuit to work. Today, general-run transistors are very , very good, and nearly identical. Designers have learned to design circuits that are tolerant of variations as well.

In general, put in general purpose devices unless you KNOW that something special is needed.

Some may need to be matched like phase shifter,
Some may want higher hfe or lower.
But in general, any "general purpose" transistor will work.

There are still different types of TO-92 devices. Phase shifters tend to use JFETs, which are not even similar to bipolar devices or MOSFETs. JFETs and MOSFETs don't have "hfe" as such, they have transconductance, and they need depletion bias or enhancement bias, depending on the type. You still have to get that part right. It's like livestock. If you want to produce milk, you need cows, not horses, and pigs are very poor to ride.

If so, what is the "sound" difference between 2222 and 3409, with the same hfe?

Best guess is no sound difference at all. There are long arguments in the audio world about the difference in sound between copper wire that is ordinary and copper wire that is oxygen-free. And about the difference in "sound" from polyester to polystyrene insulation in capacitors. In most cases, the tone/sound of a circuit is just that - the circuit, not the transistor. That " better design" thing shows up. EEs learned to design circuits that deliberately depend on resistors and capacitors to define sound and far, far less on the quirks of the transistor.

[Fancy Lime]

The "sound difference" is mostly whatever you imagine it to be.

In most circuits that are not fuzzes, you cannot go wrong with a high hfe low noise device. You will need NPN types way more often than PNP but it is wise to also get some PNP equivalents. The most common and cheapest NPN high gain low noise types are usually 2N5088 (or 2N5089) or BC550C, depending on what continent you are on or what store you buy from. These will cover you at least 90%, probably 99% of the time, even when the schematic calls for a different NPN. PNP equivalents are 2N5087 and BC560C, respectively. Low gain devices like 2N3904/2N3906 can almost always be substituted with high gain types, except in fuzzes. High(ish) current types like 2N2222/2N2907 (NPN/PNP pair) or BC337/BC327 are rarely necessary for audio in pedals but can be handy for driving tiny speakers or switching on lots of LEDs. High voltage types like 2N5551/2N5401 are usually unnecessary unless you are building tube circuits.

For the classic fuzz circuits from the 60s, all predictions are mute. These circuits can be very sensitive to hfe and other parameters. For experimentation with these, get a variety of different transistors. The weirder the better.

Cheers,
Andy

[ElectricDruid]

The weirder the better.

It's a good rule to live by!! 

[PRR]

> Keen's Second Law: When in doubt, whip in a 2N5088.

Yes.

The BC550 is a great part: for pilot lamps, small power drivers, and oddly for transformerless low-Z mike inputs (big fat junctions). I think it comes from a gaggle of computer core drivers? (Half-amp pulses for magnetic donuts.) Yes, modern '550s will work in very low-current jobs too (ones from 1973 may not). But in a rational world, the '550 costs a penny more than a 2N3904.

I'm only half convinced transistor design "improved". There are better write-ups. Also SPICE tools for fumbling to a solution. IMHO what helped is decent parts for pennies, so you can readily afford several in self-regulating connection.

2N3904 workalikes (literal rejects) worked fine in almost all my creations.

[Fancy Lime]

I've heard the current argument before but I'm not sure I understand what you mean. Why would a BC550 not work in low current applications and why would it be more suitable for high current applications than a 2N5088? The max continuous collector current for both parts is the same (100mA as per the spec sheets) and the max collector and emitter cutoff currents of the BC550 are 3 to 10 times lower than those of the 2N5088 (under similar but not identical testing conditions because why would manufacturers ever use the same testing conditions  ).

In a rational world, yes, the 2N3904 should be the cheapest transistors money can buy. However, that's not the world we live in, apparently. I just checked a bunch of stores in Europe. Result: BC types are usually the cheapest and all cost the same within each store. A  single BC550C can be had for about 0.08€ at just about every street corner, often much less, especially if you buy in bulk. 2N5088 are hard to find at all and mostly confined to specialty guitar pedal diy shops, unless you buy a lot of them. Buying a single 2N5088 will set you back around 0.50€ without shipping, sometimes more. Amusingly, 2N5089 and MPSA18, which are the same part as 2N5088 only with higher minimum hfe and better noise specs, are often cheaper. That is, if you find them at all. I suspect that Keen's second law is distorting the market. Even more amusingly, the humble 2N3904 has the largest relative price span, from 0.05€ at general electronics stores to well over ten times that in some diy guitar pedal places.

TL;DR
1. See what you can get locally for a reasonable price.
2. Check the spec sheets.
3. Most transistors will do most jobs in guitar pedals fine, as long as the are the right type (NPN, PNP, N-JFET, P-JFET, NMOS, PMOS...). Some caveats apply for all FET types due to much larger tolerances compared to BJTs.
4. Beware when a minimum hfe, minimum current handling capability, or matching of several transistors are necessary.
5. If you can get a big box of 2N5088, 2N5089, MPSA18, BC549C, or BC550C for cheap, get those and know that you have probably sorted out your NPN needs for good.

Andy

[Phend]

My original mid 70's Muff Fuzz has a BC239 and a BC239C. Why were those selected ? Hum, bet electro harmonics got a box full. During that time period, knowing nothing about this "stuff", I scavenged unknow transistors and copied the simple circuit. It worked. Yes it fuzzed well so I built 2 in series, worked even better. So there you go, slap in a transistor and what do you know, it works.

Correction: electro-harmonix

[R.G.]

My original mid 70's Muff Fuzz has a BC239 and a BC239C. Why were those selected ? Hum, bet electro harmonics got a box full.

There are stories about the varied transistors and part values in electro harmonix pedals from the 70s. The EH offices were near Canal St in NYC (so the story goes) and they'd go to the electronics surplus places on Canal St and get whatever they could, bring it back to the office/factory, and build up the next batch. Don't know the actual truth, but that's the story. In general, EH stuff from that era could have supported the myth.

[PRR]

get whatever they could

If you go back far enuff: once there were really only two *affordable* transistors: "RF" 1MHz and "Audio" 10kHz.

[amptramp]

I generally use PN2222 transistors.  Available locally, so I can pick them up and be back home in an hour, round trip.  These are TO-92 plastic 2N2222's that are good for switching.