[sdiy] odd behavior of transistors

[mark verbos]

jhaible wrote:

>>In my current project I have used a 2N3904 at the trigger input. I
>>noticed today that this transistor was responding backwards to the
>>triggers! That is it was opening with a ground and closing with a gate.
>>
>>I pulled the part out and put another in. Problem solved. Does this
>>
>happen?
>
>If the transistor was used as a logic inverter, and was damged such that
>BE is open, but BC is shorted, something like you described seems
>possible.
>
hmm. Interesting.

>
>>Has anyone in Germany noticed a high margin of bad parts in orders form
>>Reichelt? I have found at least one bad chip on each channel of my new
>>sequencer. That's 5 chips that didn't work from the onset. When they
>>were replaced by chips from another source, everything was fine. They
>>have been 4067, 4514 so far, plus the 2N3904. Am I the one who's crazy?
>>I guess that's why they're cheap.
>>
>
>I have never received _bad_ parts from Reichelt, but a lot of _wrong_ parts.
>
>The LP324 instead of LM324 was the most recent example. (I guess the read
>"improoved" in the data sheet and think they can just "upgrade" you without
>asking.)
>
>Same for NE5517 instead of LM13600. Just not the same thing.
>
>The *worst* thing are HCMOS chips instead of 4000 series CMOS.
>I almost *bet* that your "4514" is actually a ST "HC4514", which is
>in fact ST's version of the 74HC4514 (4000 series functionality
>adapted to 74HC family technology) and *not* a version of the
>CD4514, MC14514 or HEF4514. So you have a 5V chip with 6V
>maximum rating, not a 15V chip with 18V rating.
>At least this is what happend to me.
>
These are CD4514BCN (I guess they're from Barcelona! ;) I now have 3 
dead ones in the graveyard. Looks like one finally worked now though!

>
>
>Recently I got "V4007" when I ordered Reichelt's "MOS4007".
>I think these are surplus DDR (GDR) clones of the 4000 series,
>but I may be wrong and it's something else. At least these *work*
>on 15V. (;->)
>
>I had a lot of discussions with Reichelt about similar incidents.
>There is no hope - they say we are unexpensive, what dou you
>expect. (I'm paraphrasing.) And in a way they are right - they
>are cheap. And they always offered to take the wrong parts
>back. And they are the best (only?) source of Japanese semiconductors
>in Germany, so I'll still buy from them, despite some irritation.
>
Since Farnell's prices MORE THAN DOUBLED in some cases, when the Euro 
came. i will only use their competetors. Jerks.


mark