wrote:



Try sourcing obsolete types to match what was used in the 70s or 80s
and you will get sold substitutes or fakes.

Motorola brand ( or ON) MJ802s, MJ4502s and 2N3773s sold today are
not - they are just relabelled MJ15003/4s and MJ15024s.



Perhaps down-under that last statement is true. But here in the US,
adjacent to Mexico, ON is still a viable brand.


** Never suggested otherwise.

Whether they re-label or not in actuality, they *say* not.


** Really - where ?

In any case, those I have purchased through Mouser have been very, very good.


** Of course, MJ15003/4 devices are class leaders as are MJ15024/5s.

Take a look at the disclaimer at the end of this datasheet:

http://pdf1.alldatasheet.com/datashe...OLA/MJ802.html

" Motorola reserves the right to make changes without further notice to any products herin." This is to be taken quite literally !!

What they have been doing for decades is to upgrade and update the chip design of certain products at regular intervals - but keep using the same, very popular part number. The data sheets are not updated to indicate such changes.

Manufacture of the legacy chip is then dropped in favour of the new one.

When a part is obsolete ( ie sales fall to a low level) they continue to offer the part by number but supply a modern equivalent that has superior specs. This is the case with MJ802, MJ4502 and 2N3773 to my certain knowledge.

For proof, you need to slice open a few examples of different vintages and see how the chips inside are quite different.

No doubt this makes good business sense for Motorola/ON but confuses the hell out of folk who believe what they read on packages tells you what is inside.

Prices charged for legacy type numbers are significantly higher than for modern parts too - so it is both pointless and expensive to buy them.

I have not noticed other semiconductor makers doing likewise - improved chip designs are given new numbers or a suffix so the buyer knows they have something with differences.


.... Phil