EMRFD Message Archive 2380
Message Date From Subject 2380 2008-11-11 07:32:52 Paul Anderson Substituting for a 2N2222? 2381 2008-11-11 07:44:42 Graham Re: Substituting for a 2N2222? These days, both the recent production 2N2222 and 2N2904 are pretty
transistors, move variable by the source (manufacturer) than what the
part number would tell you. If it is an application below 10 MHz, they
are likely interchangeable. It is certainly worth trying the substitution,
as an experiment.
2386 2008-11-11 19:33:06 Allison Parent Re: Substituting for a 2N2222? The answer is yes for many things but not all cases.
The difference is the 2n3904 is not as high a power device nor does it
have the same peak current capability. For a lot of simple amplifiers
that use or run at less than 20ma collector current they swap very
easily. The 2n2222 is better suited for applications that need to
stand a bit more power or ahve higher collector current requirements.
I keep a huge supply of 2n2222A, 2n3904 and 2n3906, 2n7000, 2n5179
plus MPF102 as that solves my needs for a wide spread of
applications. When I need something else its 2n3866, 2n5109,
2n2907, 2n2219 or J310. Outside of that then were in the realm of
parts that I tend to use few of and have special characterstics.
2387 2008-11-11 20:56:13 wimmie262000 Re: Substituting for a 2N2222? 2389 2008-11-11 20:56:17 Glen Leinweber Substituting for a 2N2222? 2N3904 is smaller than 2N2222 - a bit better for high
frequency. 2N2222 is better for higher current or
switching higher power on and off - it can handle bigger
currents than 2N3904.
For most applications that don't push the edge of
the envelopes described above, they can be substituted.
2N4401 is also similar to 2N2222 but has slightly less
Have also looked at Asian equivalents of 2SC1815
and 2SC945. These have different pin-out
but are used generically, like 2N3904 or 2N2222.
2404 2008-11-15 08:17:58 Ashhar Farhan Re: Substituting for a 2N2222? even the 'audio' bipolar transistors do well into the lower vhf range.
it is best to perform two checks on any transistor :
1. Is the Ft at least 5 times (10 is preferable) the operating frequency?
2. Is the power dissipation about 3 times what it will undergo.
the rest are not as important as it would have been earlier . now most
designs use negative feedback for stable and consistent gain (hence,
the gain is not dependent upon the transistor's beta). this is one of
the big design gains we (homebrewers) made since the days of SSD.
2405 2008-11-15 21:07:37 Russell Shaw Re: Substituting for a 2N2222? Ashhar Farhan wrote:
> even the 'audio' bipolar transistors do well into the lower vhf range.A good figure of merit to get more gain is a small rbb'.Ccb time constant.
> it is best to perform two checks on any transistor :
> 1. Is the Ft at least 5 times (10 is preferable) the operating frequency?
> 2. Is the power dissipation about 3 times what it will undergo.
> the rest are not as important as it would have been earlier . now most
> designs use negative feedback for stable and consistent gain (hence,
> the gain is not dependent upon the transistor's beta). this is one of
> the big design gains we (homebrewers) made since the days of SSD.
2406 2008-11-16 12:14:45 Lasse Soldering fine pitch SMD I am about to start assembling several projects with fine pitch IC's and
realize my current soldering equipment is not up to the task :)
After reading about all sorts of very delicate soldering equipment, I
just stumbled acrsso the Ersa and it's solder well tip i.e. a hollow tip
hold a small almout of liquid tin and you drag the tip across the
IC-leads letting capillary forces do the trick..
Has any one here tried this, looks pretty smart, and you do not have to
clean up the mess using de-soldering braid.
Draw back is the initial cost for both the soldering station and the
Or does anyone have a good reccomendation on what soldering station to
get for this kind of work
2407 2008-11-16 13:37:54 leon Heller Re: Soldering fine pitch SMD ----- Original Message -----
2408 2008-11-16 14:33:20 Lasse Re: Soldering fine pitch SMD Thanks for the info Leon!
What type of flux do you prefere??
I see Stannol offers a few different types and applied with a pen.
leon Heller skrev:
> ----- Original Message -----
2409 2008-11-16 17:17:16 michael taylor Re: Soldering fine pitch SMD 2410 2008-11-16 19:18:24 kerrypwr Re: Soldering fine pitch SMD I invested in a microscope earlier this year.
I can solder each pin of the SSOP devices with an ordinary soldering
station iron with a fine tip.
I'm about 75% of the way through assembling the PCB for an N2PK VNA;
with my 64-y-o eyes I don't think I could have done it without the
2411 2008-11-17 07:20:19 timshoppa Re: Soldering fine pitch SMD 2412 2008-11-17 09:48:52 Steve Re: Soldering fine pitch SMD Kerry,
Did you devise a way to hold the PCB in place under the microscope? How
about a way to hold the SMD component in place on the PCB while you solder?
I build the N2PK VNA a couple of years ago and I think the major
recurring challenge was to hold the board still and to hold the
component in place for soldering. If you have some tricks, I'd be
interested in learning. :-)
> I invested in a microscope earlier this year.
> I can solder each pin of the SSOP devices with an ordinary soldering
> station iron with a fine tip.
> I'm about 75% of the way through assembling the PCB for an N2PK VNA;
> with my 64-y-o eyes I don't think I could have done it without the
> Kerry VK2TIL.
> Yahoo! Groups Links
2413 2008-11-17 10:06:57 Robert Cerreto Re: Soldering fine pitch SMD Steve,
Ever try double sided tape? I use a piece under my PCB's when they get itchy feet and want to run away.
2414 2008-11-17 10:18:48 Robert Cerreto Re: Soldering fine pitch SMD Hey Loen,
Got a part number on that tip? I have a Metcal but, can't seem to find the tip.
BTW Our "experts" at work use the drag and solder technique on all their customer reapairs.
thanks es 73, Bob WA!FXT
2415 2008-11-17 11:14:05 leon Heller Re: Soldering fine pitch SMD ----- Original Message -----
2416 2008-11-17 12:33:44 kerrypwr Re: Soldering fine pitch SMD Steve & others;
I have opened a file in Photos; "Kerry VK2TIL".
There is a photo called "Microscope".
My microscope came from a dealer (in a small way) here in VK.
Many of the 'scopes he gets don't have a stand; I think that the
institutions they come-from change the 'scopes but keep the
high-tech/cost boom mounts.
He supplied a new Dremel drill stand that is a very solid mounting for
the 'scope; a real "homebrewer's idea". :)
I made a shallow inverted-U-shaped "shelf" from aluminium; it sits on
the bench straddling the 'scope base. There is an anti-static
computer mouse pad stuck to it with a few spots of silicone.
You can see this in the photo.
It helps to fit ordinary PCB spacers to the holes in the PCB; that
gives four "feet" for it to sit on and it's very stable.
Otherwise; no tricks, just the usual methods found on the 'net &
elsewhere. You can see the obligatory tweezers & toothpick in the
It's just "Patience et longueur de temps .......". :)
2417 2008-11-17 17:22:16 Ed Culbertson Re: Soldering fine pitch SMD http://www.zianet.com/erg/SMT_Soldering.html
IF sceptical try
2418 2008-11-17 17:40:25 bob bailey Re: Soldering fine pitch SMD 2427 2008-11-19 18:12:19 Dan Reynolds Re: Soldering fine pitch SMD I too finely tried it.
It works just like they show you. The first board I tried it on, I
used flux. Really, all the flux did was make a mess, you don't need
flux with this method, it's in the paste.
The next board I just used the paste (building up a DDS30 board) and
it worked like a charm. And it sure is neat doing the WHOLE board at
once. I had a couple of traces