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Part Numbers?

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axro

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Is there any rhyme or reason to part numbers? Or it it whatever the companies want?

Like I realise that in a LM7805 the 5 is because it puts out 5 volts. What does LM mean? Or any of the other various letter and numbers that companies put on part names.
 

Chippie

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iirc,LM is the prefix used by National Semiconductors...
( along with a few other companies....Fairchild for one....)

78 is just the series, 05 signifies that it's a 5v reg...Just like a 7812 is a 12v version....

Then there is the negative rail version...7905 etc....


and then there is the uA7805....it goes on....

Manufacturers are a law unto themselves...there does not appear to be any kind of sensical approach to device id...

Unlike valves...DF,EF PL, DY, PY,EY etc...the letters denoted firstly heater voltage or current, second charachter denoted if it was a pentode (F or L), rectifier (Y) followed by numbers...

DF91, would be a 1.2volt heater, pentode, with a B7G base,

or PL504, would be a power pentode with a 300mA heater current on a B9D base...

Of course this nomenclature was originally adopted by Mullard/Philips, other manufacturers produced the same valve but with a different numbering system...a DF91 had an equivalent of 1T4...

An interesting subject...
 
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