Hi Greg,

On 11-Feb-04, Greg Mayman wrote to George White:

 GW>> And one manufacturer who would supply 5 different diodes for the
 GW>> same number, depending on which factory it came from... They
 GW>> ranged from the very good (glass encapsulated) through the usual
 GW>> to the rubbish (plastic which wasn't properly protected).

 GM> Yes, I've seen that kind of thing.

 GM> But the one I'm thinking of was a selection of completely
 GM> different types. One manufacturer used this number for small
 GM> signal diodes, another used it for power rectifiers, and so on.

 GM> It happened in the early days when registration of the new
 GM> 1N-types was done at many different offices across the country,
 GM> and communication was most likely only by snail mail.

 GM> It was a low number, it may have been a 1N21. But it is a long
 GM> time ago and my memory of it is hazy.

 GM> I do remember that when I heard about it, I checked in the
 GM> D.A.T.A. book and sure enough there were all the different types
 GM> listed against their respective makers.

Pain, fortunately I didn't come across that...
What I did hear of was the LOP switching transistor that caused one
manufacturers TV sets to go up in smoke. The developers used one
manufacturer, the factory purchasing got a better(?) deal from another
company. Unfortunately the secondary characteristics were not the
same, and not good enough, so Poof!, the set went up in smoke...
We approved both the device _and_ the suppliers. Puchasing could
not use an unapproved supplier...

 GW>> They couldn't guarentee supply from the good factory, or even the
 GW>> acceptable factorys, so we wouldn't use them (we were talking
 GW>> reasonably large volumes, >100k parts/year).

 GM> That sort of service is quite impossible! Was there no chance of
 GM> finding an alternative type from a more reliable source?

They _were_ a bog standard type, 1N4003. Plenty of alternative
suppliers available. In fact I think our call was about 150k/year.

 GM> No, what he needs is one that goes from uniploar to bipolar. The
 GM> 1489 receiver chip converts bipolar into unipolar.

 GM> The 1488 quad RS232 transmitter is the one to use. Of course it
 GM> inverts the signal, but that need not be a great problem.

Oops! Of course...

George

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