|Re: transistor equivalence|
Message #4 Posted by Tony Duell on 24 Jan 2011, 4:16 a.m.,
in response to message #3 by Alberto Fenini
Some general information on HP part numbers :
HP assembly part numbers (like PCBs, etc) have part numbers consisting of 2 5-digit groups, the first groups seems to be the model number of the instrument that first used that assembly, with leading zeros added. So the CPU Control PCB in an HP98x0 is a 09810-66513 (it was first used in the HP9810 calculator).
HP component part numbers consist of 2 4-digit groups. The first group gives the type of component. There are tables in a few HP instrument manuals, but not all.... Anyway, for transistors :
1850-xxxx = Germanium PNP
1851-xxxx = Germanium NPN
1853-xxxx = Silicon PNP
1854-xxxx = Silicon NPN
1855-xxxx = FET
1858-xxxx = Transistor array
To save space on small transistor packages, sometimes only the last digit of the first group and the 'significant digits' of the second group are printed on the package. So if you find one marked 4-471, that's an 1854-0471 silicon NPN transistor.
I wonder if one of the groups of digits on the OP's transsitors is actually a date code.