Morning. Do you know how to determine the year of production for LM320 and LM340 if the date code does not show the full year?
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FYI. The ones used on the original Apple-1 are dated YYMM
Different manufacturers may use different methods of marking the date. However, the most common was a four-digit number, with the first two digits representing the year and the next two digits representing the week. For example, 8113 represented the year 1981 and the 13th week of that year
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do you know when did vendors stope prodice LM in case with long ground?
do you think what is year on left one
The regulator on the left was made recently (or re-marked), as its logo did not exist in the 1980s.
In general, any component with precise, laser-marked labelling is either recent production, or a fake.
The different heat spreaders (which are not ground tabs: they are connected to the package's middle pin, which can be a voltage other than ground) are because these are two different package types. The left one is a TO-220 which is still a very common type, made by multiple manufacturers. The right one is a TO-202, also called "Durawatt", which was only made by National Semi long ago. This information is contained in databooks for the "linear" line of chips from National.
The part code suffix for the left chip is "T" corresponding to TO-220. It is a +12 V regulator, LM78M12CT.
The part code suffix for the right chip is "P" corresponding to TO-202. It is a –12 V regulator, LM79M12CP.
The "M" in both is a current limit. They are only specified for up to 0.5 A loads.
By the scratches around the mounting screw hole, these are clearly pulled used parts.
By the way, "TO" stands for "transistor outline" and is a specification for the exact dimensions of a package from JEDEC.
Thank you very much for the explanation, Robespierre.
I didn’t know about the logo, ground and “Durawatt.”
I was aware of the “M,” but I found information indicating that the Apple-1 has a current on +12V of less than 0.5A.
It seems I’m having no luck finding an LM with the correct date code.
One question, please: what socket do you suggest using?