
Current Sources Improved
mjmorano/Precision-Current-Source
Once it's uploaded connect the Arduino pins to the 6 pin header on the current source as follows:

The FMMT614TA is a darlington Transistor made by Diodes Incorporated in a SOT-23 package with 3 pins. -55℃~+150℃@(Tj) 1.5V 1.7V 100V 10uA 14V 15000 1V 500mA 500mW NPN SOT-23 Darlington Transistors ROHS.
PCBKit's library has its footprint (Package_TO_SOT_SMD:SOT-23, from KiCad's library), ready for a KiCad board. 455 are in stock at JLCPCB (part C99266). 1 open-source board in 1 repository on GitHub use it.
The library has no symbol for this part yet.

mjmorano/Precision-Current-Source
Once it's uploaded connect the Arduino pins to the 6 pin header on the current source as follows:
<iframe src="https://pcbkit.io/embed/parts/diodes/FMMT614TA" title="FMMT614TA in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe><img src="https://pcbkit.io/embed/parts/diodes/FMMT614TA.jpg" alt="FMMT614TA" width="1200" height="900">[](https://pcbkit.io/parts/diodes/FMMT614TA)Yes. the footprint Package_TO_SOT_SMD:SOT-23, both drawn on this page. PCBKit places them on a board for you when you design with it.
SOT-23, with 3 pins. Its footprint is drawn on this page.
Diodes Incorporated publishes it: the Datasheet link on this page opens it.
JLCPCB lists it as part C99266, with 455 in stock; the sellers' links on this page open their listings.
Parts like it in the library: the MMBTA13 by TDD, the MMBTA28 by YFW and the MMBTA13-TP by Micro Commercial Components. Check their datasheets: a part that fits the footprint may still differ in its ratings.
1 board in 1 repository on GitHub; the most starred are listed on this page, with their KiCad files.