2 pin component

This part is from a reel that is labeled as onsemi - MC78L05ACHT1G. As you can see here, this isn’t even close.

Anybody have any idea what this little bugger might actually be? There are no surface markings that I can see. I can tell you that it measures approximately 2.3mm per side, making it perfectly square. The side with the round dome is not a button, but looks to be some kind of mounting tab.

Any help would be greatly appreciated!


There are supposed to be pictures posted, but I don’t see them. Hopefully you all can!

I hope y’all can see the pictures, cause I can’t get them to actually show on my end.


We’ve got pics! We’ve got pics!

Hello, Slycer.

Device physically resembles a bottom-entry LED, similar to PN 754-1423-1-ND. Possibly an IR emitter, given its coloration, but unfortunately there are a great many ways this LED could function that have no bearing on its physical appearance. Is there any additional information on the device?

No, unfortunately I have no other info, but you are correct that it does resemble the LED you posted. I’ll have to look into the IR emitter possibility. Thanks for the suggestion!

Hello slycer2002,

Here are some other options I was able to find:

If you aren’t sure what range you have, it will be difficult to determine which one will work for you.

I think this could be one of the VEMD components. The measurements are definitely right on the money. I’m personally leaning more toward the VEMD2000X01, as the z-bend looks closer to how these pins actually look. I’m going to call this solved.

Thanks for the help!

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A couple of additional possibilities, including a couple phototransistors:

AM2520PD1BT09 Photo diode
BPT-XP2A61-TR9 Photo transistor
QSB363ZR Photo transistor

If you feel the urge to figure out whether it’s a photodiode or phototransistor, you can check how much current they conduct when an IR LED shines on them with 5V applied. Photodiodes typically conduct in the 1-20 μA range, whereas most phototransistors conduct in the 1-20 mA range.