7 Nov
2007
7 Nov
'07
3:49 p.m.
Tony Duell schrieb:
I think the difference between 74xx and 54xx is totally irrelevant here.
Nobody is going to try to use these Philips educational modules at
anything but normal room temperature.
Thinking back, I seem to recall one of the modules failed at one point.
The AND-OR-Invert chip had died. I replaced it with, I think, a 74LS51
(again, near enough) with no problems at all.
Actually, it's TTL chips. IIRC the kits came
out in the mid-1970s.
There's a schematic of the logic module in the manual (one of the frw
pages I can understand, since the manual is in German, but a schematic is
much the same in any language). There are 3 chips in the module, all with
Philis-type numbers. An FJH241 (looks like a 7404), FJH151 (7451) and
FJH231 (7401)
Actually, they don't just look like the mentioned 74xx equivalents, they
are almost (FJH241 is rather 5404). This xxxNNN convention was some European attempt to
standardize the
various logic families in the 70s;
I think this came from JEDEC as a joint venture of Siemens, Philips, and
some other vendors).
The idea was basically to have the first letter to describe the logic
family, the second a temperature range or
a sub family (e.g. Z=noise immune logic with 12Vcc), the third a
functional category. The three digit number then
refers to the actual circuit. So, an FLH101 was a TTL (F) with
temperature range 0..70degC (L), and
combinational circuit (H). The number here refers to 4 totem pole NAND-2
gates -> so this is the well-known 7400.
J in the third place denotes some flip flop or counter, K is a monoflop,
L is a decoder (e.g. 74141, 7445, 7447).
I have to look up the complete convention in some old Siemens data books.
I have at least one old Mullard (==Philips :-)) databook containing ICs
with these numbers. I'd be interested in seeing the coding, though, I
think I have soem 'FCH161' chips in the spares box...
-tony