2 Transistor Electronic Load/Source Dislike - Why?

An electronic load/source that uses only 2 transistors (3 if you count a power Darlington as 2), with the minimum of components. Always be mindful of the parameters of the TIP122, I have derated its performance to a maximum of 12 watts, on the basis of my breadboard setup and the temperature of the TIP122. The diode D1 produces an essential offset so that T1 can measure low output currents and provide good feedback. The minimum output Voltage that can be applied is about 2VDC. Applications include Battery and capacitor discharge, power supply loading, LED drive, etc. I liked this simple circuit, and can you guess what the issue is before reaching the video's end? Without further development - I do not consider this a precision electronic load.

Please consider Liking, Sharing, and Subscribing - thank you. The microphone used in this video is of my own design: https://youtu.be/01GiEWnfw8s **Please help me purchase components for more projects/repairs. To make a donation: https://paypal.me/ThankyoufromBeamer?locale.x=en_GB Contact me: beamerelectronics@gmail.com #Beamer #electronicload #constantcurrent

Notes:

• In the video I mention that a diode has a thermal drift of about 2mV/℃, I should've said -2mV/℃.

Links: TIP122 datasheet: https://www.onsemi.com/pdf/datasheet/tip120-d.pdf BC549c datasheet: https://www.onsemi.com/pdf/datasheet/bc550c-d.pdf ... https://www.youtube.com/watch?v=jCBwN6QRgF8