Olin Lathrop wrote :

> I looked at this issue before and concluded that 2N3904/3906 should be
> acceptable substitutes.

I was also loking for substitutes, but in the BCxxx line, that seems to
be more common in Europe. I don't know the 2Nxxxx line to well, but
if they are reasonable "standard", I'd guess that a standard
BCxxxC (The C types have a bit higher gain) would work.

> > The holes for the ZIF socket are tiny - the same size as those for
> > resistors and such, and on all the ZIF sockets I have the pins are
> > much too big, and "flat" in the opposite direction to ICs, so they
> > won't go into the PCB or "turned pin" IC sockets at all, and
> > conventional "flat" IC sockets are almost impossible to use because
> > the ZIF's pins are edge-on to the wiping contacts in the socket.
> > Does anyone have a favourite socket that will accept a 3M
> > (green) ZIF socket properly?
>
> It hadn't occurred to me that other ZIF sockets require
> bigger holes.  All the standard and ZIF sockets I have
> here have thin enough pins to fit in those holes, probably
> because that is a normal hole size to use for DIP ICs.
> I'm sorry, but all I can say is that the ZIF socket called
> for in the bill of materials does fit.  That turns out to be
> an Aries unit.

I have a number of 40-pin 3M/Textool ZIP's on the way
from the US to Sweden, so it's bad news if they don't fit
(easily). We'll see on monday, they are probably
at the moment at my local post office...

The 3M/Textool datasheet available from Digikey says
".012 X .030 [ 0.30 X 0.76 ]" about the pin size. The data
sheet for the Aries socket (also from Digikey) says
"0.019 +/- 0.002 [0.48 +/- 0.05]. So there is a
difference...

However, the 3M/Textool sockets seems to be pretty popular
(and the only brand available on eBay at the moment... :-) ).

> > The board is nicely designed, with everything just about where you'd
> > expect, and it's about the optimum density for hand-soldering
> > through-hole components.

Agree !

> Thanks.
>
> > Interestingly in relation to the "beginners' components"
> > topic, I had in stock all of the capacitors, all the semiconductors
> > except the transistors, half of the connectors and sockets, but
> > only five out of eleven of the resistor values, since I tend to have
> > the E12 series and most of these are E24.

Three of the values (62, 300 and 430) are only available from
the E24 series. One of the values (2K) are available from the
E24 series or higher (E96 or E192).
The rest are available from the "lower" E-series (E12).

Now, many "resistor packs" available are using
values from the E12 series (incl those I have, of course :-) ).

And, if a design uses *both* 270 ohms (an E12 value) and
300 ohms (an E24 only value) in the same design, I'd expect that
there is a specific reason to do so. If not, it could just as well
have used values from the E12 series only. In particular if
it's ment to be a device "intended for hobby and prototyping use",
as the web page says.


> I've never heard of "E12" and "E24"...

Is not that numbering system used everywhere ?

http://www.logwell.com/tech/components/resistor_values.html

Best Regards,
Jan-Erik.

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