Transformers, Coils, Chokes

[Nick]

What i did was to transplant the left hand side tube to the right and replace the 7490 and the 74141 with NOS ones that i had in stock. The original was prefixed FJJ but that was no problem.
I will put the duff one back on my HT supply and see what i can do.

I believe that "FJJ" was a Valvo prefix for "commercial grade". FJJ 141 is a plain old 7490.

In Europe and particularly in Germany they (Siemens and Valvo mainly) used their own chip numbers in the Format Fxx nnn. The 7441 decoder for instance is FJL 101. The 74141 is FLL 101 and the 74142 is FLL 151.

The commonly known 7490 decimal counter is FJJ 141 (Valvo, commercial grade) or FLJ 161 (Siemens 0 to 70°C range commercial grade) or FLJ 165 (Siemens -25 to 85°C range extended grade).

If you ever find chips with these numbers they are of German origin, often paired with the 74-series code printed as well and often with a 7xxx date code for the manufacturing date, which may add to the confusion rather than give a clue.

The year 1974 is still a bad year for reverse engineers who *think* they are dealing with a "7441" marked chip in the middle of a circuit just to find out that this chip only has been made in 41st week of 1974.

Cheers