Darlington follower

by ourcircuits

5 parts

Q1's emitter feeds Q2's base, so the cascade behaves like one transistor with roughly β² current gain, buffering the signal source from the 1 kΩ load that draws a measured 1.8–5.7 mA. The price is two base-emitter junctions in series: the output follows the input a measured 1.20–1.26 V down across the whole swing. The split is measurably uneven — Q2's junction drops 0.67–0.70 V carrying the full load current while Q1's drops only 0.53–0.56 V carrying just Q2's base current — the diode law live, in two transistors running at very different currents.