16 Nov
2012
16 Nov
'12
3:14 p.m.
On 11/16/2012 12:50 PM, David Riley wrote:
On Nov 16, 2012, at 12:29 PM, ben wrote:
The 2N2222A is a great device but a bit heavy duty for this application
and more costly.
However for high current buffer/inverter/driver it could be a good choice.
The winner is PN2222 (plastic 2n2222) and 2n3904.
I use 2N3904s a lot for switching and RF applications and it's a good
all round device.
Typically when I buy them I get 100 at a time as I use them for Zeners
(base-emitter
reversed is about 7V), Varicaps (base-collector reverse biased), High
conductance diode
(base shorted to collector) and of course as a transistor. Generally I
pay about 3-4 cents
(US) for known vendor parts.
Another device that is newer than the old bipolar transistor days are
the MOSFETs
specifically those in the 2N7000 and similar class as switches. They
offer very low
on resistance and high noise margin with the gate turn on voltage in the
3-8 Volt range.
Any one using them in quantity would do well to create a go/no-go tester
for leakage
and gain as a project like that will consume a lot of transistors and
marginal ones are
a big nuisance.
For diode the 1n914 and the 1n4148 are good choices for DRTL style logic.
Allison
On 11/16/2012 1:26 AM, Eric Smith wrote:
2N2222s should work, but they're heavy hitters. Seems like
overkill. Also, I haven't read the article in question
yet (need to dig through the thread to find the link), but
if Eric was talking about 2N3906s, those are PNP (the 2N2222
is NPN). You'd probably need to modify the schematic, if
only a little bit.
2N3906 and 2N4402 are the PNP complements of 2N3904 and
2N4401, respectively; those are probably the cheapest
general-purpose BJTs you're likely to find. I have a
general preference for the 4401 over the 3904, but it
probably doesn't make a huge difference.
- Dave It appears to me that 2N3906 silicon transistors
should work in place of
the 2G371 with only minor changes to the circuits. However, you should
test individual circuits before you build the whole computer and
discover that it doesn't work.
I was thinking 2N2222's. I took a quick
look and nothing seems to need ge transistors.
I still have to check what is PNP or NPN's so 2N2222's may not work.