Re: Transistor replacements
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Lee,
Many thanks for the reply. I'm absolutely sure that you and the community created the best design with what was available at the time.
Once again I am out of luck. TME, being in Poland, and thanks to Brexit, doesn't ship to the UK for the time being. So I will take the risk and order the SMD equivalents (MMUN2212LT1G , NSVMMUN2112LT1G),? with a bit of effort I think I can fit them on the board.
Flavio
flavio@... wrote:
> I am sourcing the components for the Z80MC, which have brought me to a
> halt trying to find the pre-biased transistors Q1-Q5 used on the front
> panel (FJN3303R, FJN4303R) and even their equivalents (NTE2358,
> NTE2357).? The TO92 versions all seem to be out of production... Are
> there any other equivalents that could be used instead? Glad if anybody
> could point me in the right direction.
These "pre-biased" transistors with internal resistors have been around
for decades, and there are hundreds of part numbers. When I designed
them into the Z80MC, all the major distributors stocked them for a few
cents each.
I buy my PC boards and parts to go on them in batches; so I still have
enough of the FJN3303R and FJN4303R transistors for kits, and to supply
customers who bought the bare boards from me. If that's the case, let me
know. :-)
But the age of through-hole parts is coming to an end. Surface-mount
parts are everywhere; but through-hole versions of the same parts are
disappearing. Digikey and Mouser sold their remaining inventories to
Rochester Electronics. Rochester is a good outfit; but they have a $250
minimum order. For a 3-cent part, that means buying >10,000!
I added the NTE equivalents to my manual. NTE has long been a supplier
of replacement parts for service and repair. They buy a standard part,
add their own part#, and jack up the price. They maintain inventory,
which costs money. So if you only need one, and don't care what it
costs, they've got it!
It doesn't help that manufacturers don't use generic 2Nxxx or 2SBxxx
numbers any more; they hide them with their own "house" numbers, so you
can't easily cross-reference them to other parts. When searching, use
the term "pre-biased transistors" to find them. There are *lots* of
equivalents (especially surface-mount); but they've made them hard to find.
Octopart.com is a free search engine for electronic components. They'll
show who has (or says they have) stock on parts such as these. At the
moment, they list:
NTE2357 NPN $1.20 each
NTE2358 PNP $0.78 each
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
? ? ? ? ?-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377,
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Zanchius