Check yer pinouts!

[Mark Hammer]

Working on Motohiko Takeda's VCO circuit, it called for one of those 5-pin matched NPN pairs (2SC1583, I guess), and lacking one, I tried looking for a comparable pair of NPNs.  I pulled out the drawer with the 2SC945s in it, and started plugging them into the meter socket to find two that were kinda sorta similar (yes, I know hfe is NOT the same as "matching").  Surprise surprise, what was ECB on this one was EBC on the next one.  What the....?

I tested a bunch of others and soon saw that the C945s from one manufacturer were ECB and those of a different manufacturer were EBC.

So the lesson is clear, kids: check yer pinouts, and don't just rely on the one datasheet you might have!

[amz-fx]

Good advice!

Another common part that deserves special attention is the 2N7000 mosfet. It may have different pinouts than other TO92 mosfets and putting it in the circuit with the wrong orientation will likely damage it.

Best regards, Jack

[GGBB]

Good advice!

Another common part that deserves special attention is the 2N7000 mosfet. It may have different pinouts than other TO92 mosfets and putting it in the circuit with the wrong orientation will likely damage it.

Best regards, Jack

I experienced that recently playing around with MOSFET clippers - swapped in BS170s and got a very different result! Pinouts were upside down relative to the device body.

[Rob Strand]

Japanese transistors (2SA=A prefix, 2SB=B, 2SB=C, 2SD=D) pretty much always use that pinout.

The EU and US transistors each have their own more common pinout.  There's a few exceptions to the US case.
Some Japanese JFETs reverse the pinout even though they are 2SK's.

It's worth sticking these on the wall,






****
I've updated the MOSFETs
There was a problem with the BS170.
All 2N7000's use the right MOSFET pinout.
All BS170's use the left MOSFET pinout
The Zetex BS170P uses the right pinout (same as 2N7000, that's odd one).
As far as I could see it's only the P that is different.

(Caution: Vishay datasheets use top view pics.)

[Mark Hammer]

Japanese transistors (2SA=A prefix, 2SB=B, 2SB=C, 2SD=D) pretty much always use that pinout.

It was precisely that assumption that had me scratching my head when the second C945 I inserted into the socket refused to register normally.  T'was only after some rotating around that I learned it was EBC and not ECB.

(And just in case anyone was wondering, no these were not bought from a Chinese retailer through Aliexpress).

[Rob Strand]

(And just in case anyone was wondering, no these were not bought from a Chinese retailer through Aliexpress).

IIRC, Fairchild did a C945.

It's an extremely common transistor.   It kind of got shifted down the ladder to general purposes jobs as the Japanese started to produce more job specific devices (these later parts were excellent).