BC547 Pinout
BC547 NPN Transistor · Common European NPN small-signal transistor. Note: its pin order is the reverse of the 2N series!
🛑 TO-92 with the flat face toward you and the pins down, left to right is C-B-E — the reverse of the E-B-C of the 2N2222/2N3904, which is the most common wiring mistake.
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | C · Collector | Output | Collector |
| 2 | B · Base | Input | Base (control) |
| 3 | E · Emitter | I/O | Emitter |
How to read the BC547 pinout
- 01
Find pin 1
One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.
- 02
Count counter-clockwise
Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.
- 03
Check the table below
Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.
Frequently asked questions
Does the BC547 have the same pinout as the 2N3904?
No! The BC547 is C-B-E, while the 2N3904/2N2222 are E-B-C (all with the TO-92 flat face toward you). Always double-check when swapping parts; wiring it backwards will not work and may even damage it.
What is the PNP complement of the BC547?
The BC557 (same C-B-E order).
Pinout data comes from onsemi/Philips BC547 datasheet (standard TO-92 numbering). Refer to the actual device datasheet as authoritative for the pinout.