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BC547C NPN General-Purpose Transistor — TO-92, 45V, 100mA, hFE 420–800 (50-Pack)
BC547C NPN General-Purpose Transistor TO-92, 45V, 100mA, hFE 420–800 (50-Pack)
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BC547C NPN General-Purpose Transistor — TO-92, 45V, 100mA, hFE 420–800 (50-Pack)
The BC547C is a high-gain NPN general-purpose transistor in a TO-92 through-hole package, rated at 45V collector-emitter voltage and 100mA continuous collector current. The “C” suffix denotes the highest gain grade (hFE 420–800), making it ideal for low-level signal amplification, audio preamplifiers, and sensitive switching circuits where high current gain is required. It is one of the most widely used small-signal transistors in electronics education and prototyping.
Key Specifications
| Parameter | Value |
|---|---|
| Package | TO-92 (through-hole) |
| Type | NPN silicon transistor |
| Collector-Emitter Voltage (VCEO) | 45V |
| Collector-Base Voltage (VCBO) | 50V |
| Continuous Collector Current (IC) | 100mA |
| DC Current Gain (hFE) | 420–800 (Grade C, at IC=2mA) |
| Transition Frequency (fT) | 300MHz |
| Collector-Emitter Saturation (VCE(sat)) | 0.2V typ. (IC=10mA, IB=0.5mA) |
| Operating Temperature | -65°C to +150°C |
| Quantity | 50 pieces |
BC547 Gain Grade Comparison
| Grade | hFE Range | Best For |
|---|---|---|
| BC547A | 110–220 | General switching, standard gain |
| BC547B | 200–450 | General amplification |
| BC547C | 420–800 | High-gain amplifiers, sensitive circuits |
Why Choose BC547C?
- High gain (hFE 420–800) — Grade C provides the highest gain for sensitive amplifier and Darlington pair designs
- 300MHz transition frequency — suitable for audio and low-RF frequency applications
- TO-92 through-hole — breadboard-friendly, easy to prototype and replace
- Industry-standard pinout — CBE (Collector-Base-Emitter) pin order, compatible with BC548, BC549, 2N3904 (verify pinout)
- 50-pack value — sufficient for lab stock, multiple circuit builds, and education
Compatible With / Common Use Cases
- Arduino GPIO switch: Drive a relay coil (50–100mA) from Arduino 5V GPIO via BC547C base resistor (4.7kΩ)
- LED driver: Drive high-brightness LED (20–50mA) from 3.3V MCU GPIO with current limiting
- Audio preamplifier: Common-emitter amplifier stage for microphone or sensor signal conditioning
- Darlington pair: BC547C + BC547C for ultra-high gain (>100,000) in sensitive detector circuits
- Oscillator circuit: Colpitts or Hartley oscillator for RF signal generation
- Logic inverter: Simple NOT gate using BC547C as saturating switch
Frequently Asked Questions
Q: How do I calculate the base resistor for BC547C to switch a relay from Arduino?
A: For a 5V relay coil drawing 70mA: IC=70mA, hFE(min)=420. IB(min) = IC/hFE = 70mA/420 = 0.17mA. For saturation, use IB = 10×IB(min) = 1.7mA. RB = (VGpio − VBE) / IB = (5V − 0.7V) / 1.7mA = 2.5kΩ. Use 2.2kΩ standard value. Add a 1N4148 flyback diode across the relay coil.
Q: What is the difference between BC547 and 2N3904?
A: Both are NPN TO-92 small-signal transistors with similar ratings (45V, 100mA). Key differences: (1) Pinout — BC547 is CBE (left to right), 2N3904 is EBC. Always verify pinout before substituting. (2) hFE — 2N3904 is 100–300 (lower than BC547C). (3) fT — 2N3904 is 300MHz (same). They are functionally interchangeable with pinout adaptation.
Q: Can BC547C be used for audio amplifier circuits?
A: Yes — BC547C is excellent for audio preamplifier stages. Its high hFE (420–800) and 300MHz fT provide good gain and bandwidth for audio frequencies (20Hz–20kHz). Use in common-emitter configuration with appropriate bias resistors. For output stages driving speakers, use higher-current transistors (BD139, TIP31C).
Package Contents
- 50× BC547C NPN General-Purpose Transistor (TO-92)
