"GregS" wrote in message
...
In article nbZTf.7431$_Q.1725@edtnps89, "Dave"
wrote:
"GregS" wrote in message
...
In article ,
(GregS) wrote:
In article , "Travis
Jordan"
wrote:

Most people would just use the NTEreplacement.
I found a distributor who claims to sell this Towers
International Transistor Selector from 1977 ??

greg

The more I read the responses, the more confused I get. There appears to
be
literally hundreds of thousands of different transistors. They have
various
ratings including, but not limited to:

ECO
EBO
BCO
Ic
Ib
hFE (min AND max)
Pd in Watts

Which ones need I concern myself with? The various "cross-reference"
pages
all give different results when presented with search keywords. The most
confusing term I see is hFE... I consulted a catalog (digikey) to try to
get
a handle on how these ratings correspond to each other, the various
packages, etc. The "hFE" rating may jump from 25 to 1000 between a "40V,
1A" and a "60V, 2A" transistor. ???

What I mean is, without getting into the meat of transistor theory and
operation (yeah, I know, I've got to go there sometime), is there a
simple
way for me to pick an "equal or greater value" transistor to replace my
bad
one? For example another poster suggested TIP42C as a replacement.

Here's how they stack up

Parameter 2SB527 TIP42C
V(CBO) 100 100
V(CEO) 110 100
Ic 0.8A 6A
Pd 10 10

I was all happy until I saw the hFE rating. This is a measure of
transistor's gain. There was no absolute maximum gain given for the
TIP42C,
the value is "30" at 0.3A, so I'd imagine that might approach the value
of
"55" given as the absolute max on the 2SB527 as Ic approaches zero on the
TIP42C.

Thanks a lot for your assistance so far, I think I'll rummage around a
bit
and see if I can scare up ANY PNP power transformer rated at 100V and
1A.

I'm still showing BD140 as a replacement for a 2SC527 TO126


AHHHH, I am seeking replacement of 2S_B_527, not 2S_C_527 as you note,
above.

Raising max current usually lowers HFE, so keep it near.
As long as the voltages are above, don't worry too much unless
your driving max current which stresses max voltage limits.
Keep HFE rating near. Changing parameters too much may
cause circuit opperation changes.Generally, higher voltage transistors
have less current gain. Darlington's have a magnitude greater
HFE's


By "near", what do you mean. I looked at the hFE vs. DC amps for the TIP42C
and it appears to range from about 20 to 100, whereas the 2SB527 is spec'ed
at 55 to 300. Close enough? I can't find a curve for the 2SB527. The
NTE292 looks pretty good too with hfe of 15 to 150.

greg