What's the story on BC183's?

[jm22]

After reading how popular the BC183 silicon transistor is for fuzz, I went looking for some at Mouser, Digikey, Allied Electric, etc., and they all say it's discontinued. I did some googling, and cannot find any information about when it was discontinued or why. Does anyone know the story of the demise of the BC183, and what are some options of similar well respected silicon transistors still in production?

[MaxPower]

As far as I can tell low hfe seems to be preferred (around 70-120 give or take) for si ff.

As for which si transistors are preferred, whichever are cheapest when we need to buy some. Or maybe that's just me and Electro Harmonix.

[Electric Warrior]

Not at all. 70–120 may work fine with many germaniums, but with silicon transistors a Fuzz Face will probably need rebiasing with hfes in the 70s, as the bias depends on Q1's hfe. BC183s should probably be >120, anyway.

Dallas Arbiter used the low gainers (BC183KA) only for a very limited time. They can work well, but the voltages will be a little different and one has to watch out for part tolerances. They mostly used high gain transistors (BC108C) for good reason. The BC183L they used were high gain, juding by the voltage and hfe readings I've seen so far.

[antonis]

IMHO, what counts ia h_FE/leakage current ratio..

[MaxPower]

Maybe it was the ge versions I was thinking of. According to legend, musicians demoed a bunch of ffs to find one they liked so you may have to do a bit of tweaking to get it to sound good.

[Crater Dylan]

For what i how they are just any other medium-high (500) hfe silicon bjt, just like bc108 which has the B around 300 and the C around 500. Silicon fuzz faces are historically high hfe, and they didn't even bother rebiasing or compensating the (actual) gain of the stages. That's probably part of the bad rep of silicon ff, although they can sound very good, although different from Germanium. Anyway I don't see the reason to use them with being discontinued, except that and the fact that someone else has. At least bc108 have their pretty metal can... If you can tell me a reason they would sound different from any jellybean 3904, 5088, bc547 or any other transistor you can find in that hfe tell me.

IMHO, what counts ia h_FE/leakage current ratio..

Leakage is surely important, but so is the hfe by itself.

[antonis]

Leakage is surely important, but so is the hfe by itself.

I thought NFB loop is aimed at h_FE independency..
(among other benefits, of course..)

[Gus]

I believe a 2N2923, MPS2923 and BC107 have the same process 04 die

https://my.centralsemi.com/datasheets/LSSGP072.PDF
https://www.mouser.com/datasheet/2/68/bc107-32245.pdf

Different part numbers can have the same die. Selected for hfe or have a different pinout or metal can or epoxy body

[Gus]

Also this low hfe Si for FF is misleading just like the 1/2 power supply voltage at the 2nd collector and only adjusting the 2nd collector resistor value.
Lots of bad information on the web.

You can build a FF with High beta Si transistors, a search of this forum will show how.

Look for colorsound one knob fuzz, vox distortion booster, meathead fuzz etc. for ideas

[Gus]

double post

[antonis]

double post

Not anymore..

[Crater Dylan]

I thought NFB loop is aimed at h_FE independency..
(among other benefits, of course..)

you mean the voltage feedback bias of Q1? I don't think so, i think the benefit is mostly gain for what i remember from geofex. It's as dependent on beta as shunt feedback bias, which is surely more than a voltage divider bias.

Also this low hfe Si for FF is misleading just like the 1/2 power supply voltage at the 2nd collector and only adjusting the 2nd collector resistor value.
Lots of bad information on the web.

You can build a FF with High beta Si transistors, a search of this forum will show how.

Look for colorsound one knob fuzz, vox distortion booster, meathead fuzz etc. for ideas

Oh for sure you can! Key in my comment is "they didn't even bother rebiasing". If you adjust values for dc bias at both stages, voltage gain, even cutoff if you want, I'm sure most transistors can work.

[antonis]

I thought NFB loop is aimed at h_FE independency..
(among other benefits, of course..)

you mean the voltage feedback bias of Q1? I don't think so, i think the benefit is mostly gain for what i remember from geofex. It's as dependent on beta as shunt feedback bias, which is surely more than a voltage divider bias.

Which gain is independent of h_FE..
(as also stnads for Q2..)

[Electric Warrior]

IMHO, what counts ia h_FE/leakage current ratio..

Leakage is surely important, but so is the hfe by itself.

As we're talking silicon transistors here, we know the leakage is 0, which leaves hfe as the variable.

For what i how they are just any other medium-high (500) hfe silicon bjt, just like bc108 which has the B around 300 and the C around 500. Silicon fuzz faces are historically high hfe, and they didn't even bother rebiasing or compensating the (actual) gain of the stages. That's probably part of the bad rep of silicon ff, although they can sound very good, although different from Germanium. Anyway I don't see the reason to use them with being discontinued, except that and the fact that someone else has. At least bc108 have their pretty metal can... If you can tell me a reason they would sound different from any jellybean 3904, 5088, bc547 or any other transistor you can find in that hfe tell me.

Without the gain group letter they could be from any gain range.

With the transistors that Dallas Arbiter chose, rebiasing was not really necessary. And I don't think compensating for the increased gain was something they considered. Increased gain must have been considered an improvement.

With the fuzz control dialed back a bit, a silicon fuzz face can sound rather similar to a germanium one. The brighter tones with the fuzz pot cranked can be very useful, so there was an additional benefit. 

Oh for sure you can! Key in my comment is "they didn't even bother rebiasing". If you adjust values for dc bias at both stages, voltage gain, even cutoff if you want, I'm sure most transistors can work.

It's not as if Fuzz Faces require very particular transistors to work well. They work with a wide range of gains and leakages.