NPN/PNP ट्रांजिस्टर (TO-92) पिनआउट

पिन

Flat (marked) face towards you, legs down — the same package comes in two pin orders:
E – B – C from the left: 2N3904, 2N3906, 2N2222 / PN2222 (the American 2N family)
C – B – E from the left: BC547, BC557, BC337, BC327 (the European BC family) — exactly mirrored
The base is in the middle on both, so a swapped part still half-works (reversed, at a small fraction of its gain) — check the datasheet every time the part number changes

Example parts	NPN: 2N3904, 2N2222A, BC547; PNP: 2N3906, BC557
Collector–emitter voltage	2N3904 / 2N2222A: 40 V; BC547: 45 V (PNP versions: −40 / −45 V)
Collector current (max)	2N3904: 200 mA; 2N2222A: 600 mA; BC547: 100 mA
DC current gain (hFE)	2N3904: 100–300 at 10 mA; 2N2222A: 100–300 at 150 mA; BC547: 110–800 (A/B/C gain groups)
Power dissipation	2N3904 / 2N2222A: 625 mW; BC547: 500 mW (TO-92, 25 °C)
Transition frequency	≈ 300 MHz (2N3904, 2N2222A)
Base–emitter voltage (on)	≈ 0.65–0.7 V
Pin order (flat face, legs down)	2N family: E–B–C; BC family: C–B–E
पैकेज	TO-92