I was checking for data on an FT5154 transistor of 1976 kit.
An old German transistor data manual showed it equivalent to 2N5154.
A straight block of 50 or so others listed in that manual from FT1724 to
FT5154 showed the same 2N equivalence.
Anyone know of a general rule ?
FT??? in hundreds don't seem to have direct number 2N equivalents

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"n cook" wrote in message
...
I was checking for data on an FT5154 transistor of 1976 kit.
An old German transistor data manual showed it equivalent to 2N5154.
A straight block of 50 or so others listed in that manual from FT1724 to
FT5154 showed the same 2N equivalence.
Anyone know of a general rule ?
FT??? in hundreds don't seem to have direct number 2N equivalents

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





Sometimes the mfrs make a line of transistors having very similar
characteristics, differing in only a few specific elements, such as Vce,
Ic(max), etc. They might have numbered them sequentially, but there is (was) no
requirement or guideline to do that. Part numbers are arbitrary in most cases,
and have no correlation between manufacturers. If a manufacturer second sources
a part, then it's good sense to assign the same or very similar part number, but
again, no specific requirement.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!

DaveM wrote:

Sometimes the mfrs make a line of transistors having very similar
characteristics, differing in only a few specific elements, such as Vce,
Ic(max), etc.

Sometimes they took the same transistor and tested it. Depending upon
the results, it became one part or the other.

Back when the IBM PC first came out you could buy memory that cycled
at 200, 150, 125 or 100 ns. There was only one production line.

Each chip was tested at 100ns (10mHz), if it passed it was maked -100
and sent off to be packaged. If it passed at 125ns (8mHz) it was marked
-125, and so on. If it did not pass at the lowest speed the chips were
sold at it was tossed.

Now the chips that failed would be sold on eBay as "untested". :-)

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

Geoffrey S. Mendelson wrote in message
...
DaveM wrote:

Sometimes the mfrs make a line of transistors having very similar
characteristics, differing in only a few specific elements, such as Vce,
Ic(max), etc.

Sometimes they took the same transistor and tested it. Depending upon
the results, it became one part or the other.

Back when the IBM PC first came out you could buy memory that cycled
at 200, 150, 125 or 100 ns. There was only one production line.

Each chip was tested at 100ns (10mHz), if it passed it was maked -100
and sent off to be packaged. If it passed at 125ns (8mHz) it was marked
-125, and so on. If it did not pass at the lowest speed the chips were
sold at it was tossed.

Now the chips that failed would be sold on eBay as "untested". :-)

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice:
1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

Replaced FT5415 with 2N5415 and working fine

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"Geoffrey S. Mendelson" wrote:

DaveM wrote:

Sometimes the mfrs make a line of transistors having very similar
characteristics, differing in only a few specific elements, such as Vce,
Ic(max), etc.

Sometimes they took the same transistor and tested it. Depending upon
the results, it became one part or the other.

Back when the IBM PC first came out you could buy memory that cycled
at 200, 150, 125 or 100 ns. There was only one production line.

Each chip was tested at 100ns (10mHz), if it passed it was maked -100
and sent off to be packaged. If it passed at 125ns (8mHz) it was marked
-125, and so on. If it did not pass at the lowest speed the chips were
sold at it was tossed.

Now the chips that failed would be sold on eBay as "untested". :-)



Really? Then explain the 4164 chips of various brands marked 300
that tested to 150 or better on my RAM tester. I repaired a LOT of
Commodore 64 computers, and bad or slow memory was one of the biggest
failures. I salvaged thousands of used 4164 and 41256 chips from Unisys
mainframe memory boards. All that were still good (over 99%) tested at
least one level faster than they were marked. They told me that they
bought millions of RAM chips, speed tested them, and then sold the
slower culls to the IBM clone makers and on the spot market.

In article , Michael A. Terrell wrote:


"Geoffrey S. Mendelson" wrote:

DaveM wrote:

Sometimes the mfrs make a line of transistors having very similar
characteristics, differing in only a few specific elements, such as Vce,
Ic(max), etc.

Sometimes they took the same transistor and tested it. Depending upon
the results, it became one part or the other.

Back when the IBM PC first came out you could buy memory that cycled
at 200, 150, 125 or 100 ns. There was only one production line.

Each chip was tested at 100ns (10mHz), if it passed it was maked -100
and sent off to be packaged. If it passed at 125ns (8mHz) it was marked
-125, and so on. If it did not pass at the lowest speed the chips were
sold at it was tossed.

Now the chips that failed would be sold on eBay as "untested". :-)

Really? Then explain the 4164 chips of various brands marked 300
that tested to 150 or better on my RAM tester. I repaired a LOT of
Commodore 64 computers, and bad or slow memory was one of the biggest
failures. I salvaged thousands of used 4164 and 41256 chips from Unisys
mainframe memory boards. All that were still good (over 99%) tested at
least one level faster than they were marked. They told me that they
bought millions of RAM chips, speed tested them, and then sold the
slower culls to the IBM clone makers and on the spot market.

Did you test them at worst case conditions? The manufacturer ensures
they meet spec at all legal conditions, the slowest conditions would
typically be low voltage (-10%?) and high temperature (often 70degC,
maybe even 100degC?) so if you're testing them at room temp and nominal
voltage they'll run considerably faster.

Mike.

Remove _ for valid address wrote:

In article , Michael A. Terrell wrote:


Really? Then explain the 4164 chips of various brands marked 300
that tested to 150 or better on my RAM tester. I repaired a LOT of
Commodore 64 computers, and bad or slow memory was one of the biggest
failures. I salvaged thousands of used 4164 and 41256 chips from Unisys
mainframe memory boards. All that were still good (over 99%) tested at
least one level faster than they were marked. They told me that they
bought millions of RAM chips, speed tested them, and then sold the
slower culls to the IBM clone makers and on the spot market.

Did you test them at worst case conditions? The manufacturer ensures
they meet spec at all legal conditions, the slowest conditions would
typically be low voltage (-10%?) and high temperature (often 70degC,
maybe even 100degC?) so if you're testing them at room temp and nominal
voltage they'll run considerably faster.

Mike.


The RAM tester checked the memory at three different voltages,
(VCC-10% VCC and VCC+10%) and had a calibrated, adjustable clock to set
the test speed. Most of my testing was done at either room temperature
of 85 to 90 degree Fahrenheit, or at full operating temperature when
socketed chips were pulled from a working motherboard. I was repairing
hundreds of Commodore C64 computers, and early IBM clones with 4164 and
41256 RAM. I know there was fancier test equipment available, but I
could test or verify bad RAM in seconds. Some that were marked 300
would test at under 100, while others in same the batch tested close to
the guaranteed 300 under the same test conditions.



--
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