Transistor Hfe

[fixr1984]

Ive been reading that most of the transistors are rated at 70-120 hfe or so. I tested some with my DMM and for a 2n5087 im getting 390 hfe. Do you have to convert the number that the DMM gives you or did I do something wrong? I looked up the data sheet on it and matched up the b,c and e to the proper place on the meter. Actually that is the only way that my meter will get a reading on it. The data sheet said that the 2n5087 has a min of 250 hfe and a max of 850 hfe. Im sure I missunderstood that cause its way higher than everyone around here mentions when they refer to hfe. Please help me to understand. I did a search and came up empty.

[Paul Perry (Frostwave)]

You can easy get a Hfe that large. I've had transistors that went over the 999 max on my meter. THe reason people are always talking about low gain transistors here, is in the context of fuzz faces, where the design requires particular (low) gains.

[nelson]

You can easy get a Hfe that large. I've had transistors that went over the 999 max on my meter. THe reason people are always talking about low gain transistors here, is in the context of fuzz faces, where the design requires particular (low) gains.

Silicon xtsrs are not "victim" to the same Foybles Germ xstrs are in the low gain dept. However try to sound like hendrx without them HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA...........................................................................HA.


Cough, cough,cough,cough

010101011110100011010101110010001100010001001010010101001o00010
o01001o00o010010010110o0010001001010110010010101001100
001000100100100101010001000100010010010010100101010010
100100100110101001000100010010100101010101000100001001
0010101000100010010010001000100101010010101010.


I wish I understood binary.


PN

[no one ever]

i got a pair of silicon bc109c's from smallbear... just measure them today, one was around 470 H_fe and the other one was around 740! and no it's not because i'm dyslexic

[fixr1984]

So if i used the above transistor in my fuzz face it could be limiting the potential of it. I get more distortion that fuzz. If thats the case and im too high on hfe should i switch to a diff one? Would a high hfe reading be ideal for distortion boxes?

[R.G.]

Ive been reading that most of the transistors are rated at 70-120 hfe or so.

That's a problem. Maybe you meant that most transistors for a fuzz face should be in that range. It's actually somewhat hard to reliably find gains that low with modern production silicon devices. The common-as-dirt types are usually around 200.

Where did you read that?

Would a high hfe reading be ideal for distortion boxes?

You're mixing up concepts. Circuits matter for distortion boxes. Transistors matter only in that they make the circuits operate well. There is nothing inherent about a transistor or its gain that is better or worse for distortion boxes. It's only how they're used.  Certain circuits, notably the Fuzz Face and its million children and clones sound better with mildly low gain transistors, perhapse even germanium devices. That says NOTHING about how the same transistors would sound in another circuit.

In many circuits, the circuits have been designed to make the transistor's variable characteristics not matter much, if any. To a commercial manufacturer, repeatably getting what you expect is worth a zillion times the value of getting a few that are great. So engineers were trained to make the circuits work with the whole variation of transistor characteristics if possible. That means that most circuits are transistor-indifferent. I express this as Keen's Second Law - When in doubt, use a 2N5088. 

[fixr1984]

I had read about those low readings mostly searching layouts for the fuzzrite and fuzz face. So that would make sense then, i just was missreading, thinking that all trannys should be real low readings. Thanks a bunch for the help.

[R.G.]

Gotcha. I understand.

[Mark Hammer]

You can easy get a Hfe that large. I've had transistors that went over the 999 max on my meter. THe reason people are always talking about low gain transistors here, is in the context of fuzz faces, where the design requires particular (low) gains.

Silicon xtsrs are not "victim" to the same Foybles Germ xstrs are in the low gain dept. However try to sound like hendrx without them HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA...........................................................................HA.


Cough, cough,cough,cough

010101011110100011010101110010001100010001001010010101001o00010
o01001o00o010010010110o0010001001010110010010101001100
001000100100100101010001000100010010010010100101010010
100100100110101001000100010010100101010101000100001001
0010101000100010010010001000100101010010101010.

I wish I understood binary.
PN

Not sure if you ever saw the kids' animated show "Re-Boot" (http://www.bcdb.com/cartoons/Other_Studios/M/Mainframe_Entertainment/ReBoot/).  It took place in a digital world where everyone had names drawn from computing terms and everything seemed to make sense as long as you didn't think about it too long.  In one of the episodes ("Talent Night", I think), a talent show is held and during the auditions, one of the bizarre little digital entities comes out and does a standup comic routine....except all the jokes are told in binary.  When he gets to the punchline, he slows down, pauses, all the auditorium audience leans forward in their seats waiting, and he races through a series of 1's and 0's that leaves the audience in stitches.

[petemoore]

  I used to catch that Show. Great ...State of the Art Humor...