2N2222 Foot Print - Backwards?

I’m learning Kicad Layout and created a simple circuit with a plastic 2N2222 Transistor…
TO-92 I think.
Question 1… One datasheet shows Pin 1 as the Collector…

But others seem to show Pin 3 as the collector…

Question 2: Is their a footprint in Kicad for either footprint?
In my sample below I used the Package_TO_SOT_THT:TO-92 footprint

Qustion 3: What is the most common 2N2222 Plastic Case footprint?

Question 4: Also, is the “square” pad considered Pin 1 or considered the Collector?

This transistor is well known for having more than one pin layout. I think there’s no point asking which is more common, just make sure you buy the variant you want or are willing to select the right footprint for the stock you have. The square pad is usually pin 1.

And if Murphy decides to pay you a visit, just turn the transistor through 180 deg. with respect to the outline and bend the base wire the other way… and use a felt pen on the silk so no one sees the mistake :grin:

If I understand right, 2N2222 is the metal TO-18 version while the familiar TO-92 is PN2222…

Looking at the above posted picture, it appears not to be the case… damn those manufacturers.

Yeah, and like I wrote:

I think that (to avoid confusion) you might be better off with 2N4401 which has always been in a TO-92 and has specs which are similar to 2N2222. PN2222 would be a less standard designation.

Yes. That has been around since maybe 1965? I don’t think that TO-18’s (or the other metal can transistors) are so common these days. I would be less inclined to trust any vendor which designates a TO-92 transistor as 2N2222, 2N2219, 2N2907, or 2N2905. Those four were all metal can packaged general purpose transistors. NPN and PNP in TO-18 and TO-5 (or maybe TO-39). I am not sure but I think the TO-39 was a true hermetic metal TO-5, while some of the other metal cans are sealed with epoxy.

Regarding TO-92: Ignore manufacturer pin numbers. Those common transistors are EBC left to right as shown in the labeled package photograph. BTW pin numbers on SOT23s can also get you into trouble.

There are also some gotcha’s with other packages.
For example, with SOT23, pin 1 is not even always on the same side of the package.

There are also some SO- IC’s where the “gull wing” pins are bent upwards instead of downwards, which also results in a mirror image for the footprint.

Apart from the expected triangular pad pattern, may old designs using the TO-18/TO-5 packages were expecting the higher power dissipation and may even have used clip on heatsinks. The TO-92 variant is just not an equivalent at all

If anything, I would stock jelly bean transistors in the EBC arrangement, as this is more common than the ECB arrangement. The standard KiCad footprint library has all the permutations. This will allow you to use a wider range of parts, including the Japanese 2SC and 2SA series, and the European BC series.

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