Maker Pro
Maker Pro

Equivalent Transistor.

I am currently working on a project to regulate the speed of a
computer's case fan using a momentary switch (see http://
groups.google.com/group/sci.electronics.design/browse_thread/thread/
7cc6e2b62e9e6cbc/).

After working with one of the other users, I was able to come up with
a workable circuit based on his reference design, located here:

http://www.usenet-replayer.com/cgi/content/viruscheck?/9/8/1/3/1171353189.59.pdf

The problem is that I cannot find the specified transistors. I was
able to aquire the rest of the components with minimal difficulty, but
the Trans. are nowhere to be found.

What I need is a short list (doesn't have to be complete, of course)
of transistors that would be equivalent to a 2N4401 NPN switching
transistor. It must take a 5-volt signal (<15mA) on the base from a
TTL IC, and use this signal to control a twelve volt current not
exceeding 250 mA (The higher this maximum, the better, but less than
0.5A Max). As can be seen from the diagram mentioned above, a low
input to the transistor disables the current, while a high (~5v)
signal enables it.

This is kind of an urgent matter as tommowow will be my last
opportunity to pick them up; after which I will have to wait in agony
until Monday-not a good experience.

Cheers.
 
*Correction: Ignore the statement about 0.5A max. I was looking at
the datasheets for a 2N4401, and noticed that they themselves go up to
600 mA. No ceiling on this one.
 
R

Robert Baer

Jan 1, 1970
0
I am currently working on a project to regulate the speed of a
computer's case fan using a momentary switch (see http://
groups.google.com/group/sci.electronics.design/browse_thread/thread/
7cc6e2b62e9e6cbc/).

After working with one of the other users, I was able to come up with
a workable circuit based on his reference design, located here:

http://www.usenet-replayer.com/cgi/content/viruscheck?/9/8/1/3/1171353189.59.pdf

The problem is that I cannot find the specified transistors. I was
able to aquire the rest of the components with minimal difficulty, but
the Trans. are nowhere to be found.

What I need is a short list (doesn't have to be complete, of course)
of transistors that would be equivalent to a 2N4401 NPN switching
transistor. It must take a 5-volt signal (<15mA) on the base from a
TTL IC, and use this signal to control a twelve volt current not
exceeding 250 mA (The higher this maximum, the better, but less than
0.5A Max). As can be seen from the diagram mentioned above, a low
input to the transistor disables the current, while a high (~5v)
signal enables it.

This is kind of an urgent matter as tommowow will be my last
opportunity to pick them up; after which I will have to wait in agony
until Monday-not a good experience.

Cheers.
Cannot get the image.
Use any medium-signal NPN; that is to say, not small signal like the
infamous 2N2222 whic would be a POS in that application.
BTW, one does not drive a transistor base with voltage...
 
R

Robert Baer

Jan 1, 1970
0
*Correction: Ignore the statement about 0.5A max. I was looking at
the datasheets for a 2N4401, and noticed that they themselves go up to
600 mA. No ceiling on this one.
So you found a transistor...
 
So you found a transistor...

No, the schematic I am basing my design from calls for a few
2N4401's. However, I am unable to aquire them, because the place I
get components from does not carry any. The people who work there
(think work-study undergrads), couldn't tell a diode from a toaster,
so any querys as to what transistor would be a suitable replacement
would go unanswered. I myself confuse electrical components with
kitchen appliances from time to time as well, and I too don't know
which transistors would work (hence this Usenet post directed at
electronics experts/hobbyists). What I need is a list of parts
numbers that you can say with complete certainty, "Yes, you can use
this transitor instead of those for this application, and it will work
as required". This way when I go to the stockroom with the
elecrically illiterate, I can say "I need four 2Nxxx's. Do you carry
those? No? How about 2Nyyyy's? 2Nzzzz's?". Get what I'm saying?

If you look at the schematic, you'll see that I needed about a dozen
pieces. I have every part but the transistors, and the miniboard /
soldering equipment should be coming in the mail tommorow. I'd like
to get it all done by tommorow night, but If I don't know which trans.
to get, I'll have to wait until monday or later to get em'. Not good
news, seeing as this (moderately) simple project is about a week in
the making, and has taken varying amounts of effort from a dozen
people or so.
 
G

GPG

Jan 1, 1970
0
No, the schematic I am basing my design from calls for a few
2N4401's. However, I am unable to aquire them, because the place I
get components from does not carry any. The people who work there
(think work-study undergrads), couldn't tell a diode from a toaster,
so any querys as to what transistor would be a suitable replacement
would go unanswered. I myself confuse electrical components with
kitchen appliances from time to time as well, and I too don't know
which transistors would work (hence this Usenet post directed at
electronics experts/hobbyists). What I need is a list of parts
numbers that you can say with complete certainty, "Yes, you can use
this transitor instead of those for this application, and it will work
as required". This way when I go to the stockroom with the
elecrically illiterate, I can say "I need four 2Nxxx's. Do you carry
those? No? How about 2Nyyyy's? 2Nzzzz's?". Get what I'm saying?

If you look at the schematic, you'll see that I needed about a dozen
pieces. I have every part but the transistors, and the miniboard /
soldering equipment should be coming in the mail tommorow. I'd like
to get it all done by tommorow night, but If I don't know which trans.
to get, I'll have to wait until monday or later to get em'. Not good
news, seeing as this (moderately) simple project is about a week in
the making, and has taken varying amounts of effort from a dozen
people or so.

http://www.micrel.com/_PDF/Eval-Board/mic502_eb.pdf
 
F

Fred Bloggs

Jan 1, 1970
0
I am currently working on a project to regulate the speed of a
computer's case fan using a momentary switch (see http://
groups.google.com/group/sci.electronics.design/browse_thread/thread/
7cc6e2b62e9e6cbc/).

After working with one of the other users, I was able to come up with
a workable circuit based on his reference design, located here:

http://www.usenet-replayer.com/cgi/content/viruscheck?/9/8/1/3/1171353189.59.pdf

The problem is that I cannot find the specified transistors. I was
able to aquire the rest of the components with minimal difficulty, but
the Trans. are nowhere to be found.

What I need is a short list (doesn't have to be complete, of course)
of transistors that would be equivalent to a 2N4401 NPN switching
transistor. It must take a 5-volt signal (<15mA) on the base from a
TTL IC, and use this signal to control a twelve volt current not
exceeding 250 mA (The higher this maximum, the better, but less than
0.5A Max). As can be seen from the diagram mentioned above, a low
input to the transistor disables the current, while a high (~5v)
signal enables it.

This is kind of an urgent matter as tommowow will be my last
opportunity to pick them up; after which I will have to wait in agony
until Monday-not a good experience.

The 2N2222 will work in that application, they are cheap and abundant.
 
F

Fred Bloggs

Jan 1, 1970
0
Robert said:
Use any medium-signal NPN; that is to say, not small signal like the
infamous 2N2222 whic would be a POS in that application.


That's bull, even the PN2222A can handle 1A peak, and maintains a
minimum HFE of 50 at 250mA with VCE,sat under 0.2V. It is a general
purpose switching transistor, not small signal, and is competitive with
the 2N4401 in most applications.
 
R

Rich Grise

Jan 1, 1970
0
The 2N2222 will work in that application, they are cheap and abundant.

PN2222 is probably cheaper and easier to find. :)

Then again, it's another number to hit the stockroom kids with. :)

Cheers!
Rich
 
E

ehsjr

Jan 1, 1970
0
I am currently working on a project to regulate the speed of a
computer's case fan using a momentary switch (see http://
groups.google.com/group/sci.electronics.design/browse_thread/thread/
7cc6e2b62e9e6cbc/).

After working with one of the other users, I was able to come up with
a workable circuit based on his reference design, located here:

http://www.usenet-replayer.com/cgi/content/viruscheck?/9/8/1/3/1171353189.59.pdf

The problem is that I cannot find the specified transistors. I was
able to aquire the rest of the components with minimal difficulty, but
the Trans. are nowhere to be found.

What I need is a short list (doesn't have to be complete, of course)
of transistors that would be equivalent to a 2N4401 NPN switching
transistor. It must take a 5-volt signal (<15mA) on the base from a
TTL IC, and use this signal to control a twelve volt current not
exceeding 250 mA (The higher this maximum, the better, but less than
0.5A Max). As can be seen from the diagram mentioned above, a low
input to the transistor disables the current, while a high (~5v)
signal enables it.

This is kind of an urgent matter as tommowow will be my last
opportunity to pick them up; after which I will have to wait in agony
until Monday-not a good experience.

Cheers.

BC337 is another substitute, besides 2N2222, that
will work for you.

It's best to look at the datsheets for the transistors
the supplier can provide you. No one here has a
crossreference list to what's in stock at your
supplier.

Ed
 
R

Rich Grise

Jan 1, 1970
0
BC337 is another substitute, besides 2N2222, that
will work for you.

It's best to look at the datsheets for the transistors
the supplier can provide you. No one here has a
crossreference list to what's in stock at your
supplier.


That's the best idea - find out what they've GOT, then look up the
data sheets and find one that will work.

Just about any "general-purpose" NPN transistor should do.

Good Luck!
Rich
 
R

Robert Baer

Jan 1, 1970
0
No, the schematic I am basing my design from calls for a few
2N4401's. However, I am unable to aquire them, because the place I
get components from does not carry any. The people who work there
(think work-study undergrads), couldn't tell a diode from a toaster,
so any querys as to what transistor would be a suitable replacement
would go unanswered. I myself confuse electrical components with
kitchen appliances from time to time as well, and I too don't know
which transistors would work (hence this Usenet post directed at
electronics experts/hobbyists). What I need is a list of parts
numbers that you can say with complete certainty, "Yes, you can use
this transitor instead of those for this application, and it will work
as required". This way when I go to the stockroom with the
elecrically illiterate, I can say "I need four 2Nxxx's. Do you carry
those? No? How about 2Nyyyy's? 2Nzzzz's?". Get what I'm saying?

If you look at the schematic, you'll see that I needed about a dozen
pieces. I have every part but the transistors, and the miniboard /
soldering equipment should be coming in the mail tommorow. I'd like
to get it all done by tommorow night, but If I don't know which trans.
to get, I'll have to wait until monday or later to get em'. Not good
news, seeing as this (moderately) simple project is about a week in
the making, and has taken varying amounts of effort from a dozen
people or so.
Since the schamatic is inaccesable, i cannot help too much.
NTE cross reference shows the 2N4401 as equivalent to their 123AP
(TO-92 package, 600ma Ic max, 40Vce rating and 625mW max dissipation).
Some other types that also cross to the 123AP are: 2N117, 2N118,
2N118A, 2N119, 2N120, 2N148C, 2N148C/D, 2N148D, 2N160, 2N160A, 2N161,
2N161A, 2N163, 2N263, 2N264, 2N385/46, 2N706/46, 2N706/51, 2N706A/46,
2N706A/51, 2N706B/46, 2N706B/51, 2N708/46, 2N709A/46, 2N......., 2N4400,
2N4401, 2N4420, 2N4421, 2N4422, 2N4432, 2N4432A, 2N4950, 2N4966, 2N4967,
2N4968, 2N......, 2N5769, 2N5810, 2N5845, 2N5845A, 2N5851, 2N.... und so
wieder ad nauseum.
 
R

Robert Baer

Jan 1, 1970
0
Fred said:
The 2N2222 will work in that application, they are cheap and abundant.
....and absolute shit above 100mA.
 
R

Robert Baer

Jan 1, 1970
0
Fred said:
That's bull, even the PN2222A can handle 1A peak, and maintains a
minimum HFE of 50 at 250mA with VCE,sat under 0.2V. It is a general
purpose switching transistor, not small signal, and is competitive with
the 2N4401 in most applications.
Excuse me! The original 2N2222 data sheet indicates "small signal"
and the curves show that there are serious internal IR losses as one
goes above 100mA; if one is crazy enough to attempt even 500mA, based on
those specs, it would blow its cork!
Now the PN2222A *might* be a little better due to a different die
size and diffusion schedule.
Looking at the Fairchild data sheet, please note there are no
oerational specs or curves beyond 500mA, and those curves indicate that
operation above 100mA can result in power dissipation tradeoffs that
might not be acceptable.
Furthemore operation at your vaunted one amp is certainly not
recommended, as that is the *absolute maximum* rating!
 
R

Robert Baer

Jan 1, 1970
0
Rich said:
That's the best idea - find out what they've GOT, then look up the
data sheets and find one that will work.

Just about any "general-purpose" NPN transistor should do.

Good Luck!
Rich
That is about what i initially said..
 
F

Fred Bloggs

Jan 1, 1970
0
Robert said:
...and absolute shit above 100mA.

That's not true, the transistor has been designed for maximal Hfe in
that current range, and it is spec'd out to 500mA, which should give you
a clue. You will be calling for a 2N3055 next.
 
R

Rich Grise

Jan 1, 1970
0
That's not true, the transistor has been designed for maximal Hfe in
that current range, and it is spec'd out to 500mA, which should give you
a clue. You will be calling for a 2N3055 next.

Well, at least it wouldn't oscillate. ;-)

Cheers!
Rich
 
I mannaged to acquire a few 2N2222's, and they work fine; however,
after building the final version of the circuit, I uncovered a
separate problem which is best discussed in a separate post (IC
overheating).
 
R

Robert Baer

Jan 1, 1970
0
Fred said:
That's not true, the transistor has been designed for maximal Hfe in
that current range, and it is spec'd out to 500mA, which should give you
a clue. You will be calling for a 2N3055 next.
Lemme see now; Philips has a max spec of 800mA in the *metal* can,
and both Fairchild and Philips indicate a VCE(sat) of 1.6V (!!!) at
500mA - meaning an internal dissipation of 800mW nevermind the max
dissipation spec is 500mW.
I guess you love that loss and the smell of cooking silicon...
 
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