{"product_id":"bc547-bc557-to92-npn-pnp-transistor-assorted-kit-100pcs","title":"BC547 BC557 TO-92 NPN PNP Transistor Assorted Kit — 50 Pairs (100pcs)","description":"\u003ch2\u003eBC547 \/ BC557 TO-92 NPN \u0026amp; PNP Transistor Assorted Kit — 50 Pairs (100pcs)\u003c\/h2\u003e\n\u003cp\u003eA matched assorted kit of 50 pairs (100 pieces total) of BC547B NPN and BC557B PNP general-purpose TO-92 transistors. The BC547\/BC557 complementary pair is one of the most widely used small-signal transistor pairs in electronics, suitable for signal switching, audio amplification, oscillator circuits, and general-purpose analogue and digital circuit design. The B-grade suffix indicates medium gain (hFE 200–450 for BC547B, 200–450 for BC557B), providing consistent performance across the kit.\u003c\/p\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eBC547B (NPN)\u003c\/th\u003e\n\u003cth\u003eBC557B (PNP)\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eType\u003c\/td\u003e\n\u003ctd\u003eNPN\u003c\/td\u003e\n\u003ctd\u003ePNP\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePackage\u003c\/td\u003e\n\u003ctd\u003eTO-92\u003c\/td\u003e\n\u003ctd\u003eTO-92\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eV_CEO (max)\u003c\/td\u003e\n\u003ctd\u003e45V\u003c\/td\u003e\n\u003ctd\u003e45V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eI_C (max)\u003c\/td\u003e\n\u003ctd\u003e100mA\u003c\/td\u003e\n\u003ctd\u003e100mA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eP_D (max)\u003c\/td\u003e\n\u003ctd\u003e500mW\u003c\/td\u003e\n\u003ctd\u003e500mW\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ehFE (B grade)\u003c\/td\u003e\n\u003ctd\u003e200–450\u003c\/td\u003e\n\u003ctd\u003e200–450\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ef_T (transition freq.)\u003c\/td\u003e\n\u003ctd\u003e300MHz\u003c\/td\u003e\n\u003ctd\u003e150MHz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eV_BE (sat)\u003c\/td\u003e\n\u003ctd\u003e~0.7V\u003c\/td\u003e\n\u003ctd\u003e~0.7V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNoise Figure\u003c\/td\u003e\n\u003ctd\u003eLow (audio grade)\u003c\/td\u003e\n\u003ctd\u003eLow (audio grade)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCertification\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003eRoHS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eBC547 vs BC548 vs BC549 Selection\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003ePart\u003c\/th\u003e\n\u003cth\u003eV_CEO\u003c\/th\u003e\n\u003cth\u003eNoise\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBC547\u003c\/td\u003e\n\u003ctd\u003e45V\u003c\/td\u003e\n\u003ctd\u003eLow\u003c\/td\u003e\n\u003ctd\u003eGeneral purpose, switching, audio\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBC548\u003c\/td\u003e\n\u003ctd\u003e30V\u003c\/td\u003e\n\u003ctd\u003eLow\u003c\/td\u003e\n\u003ctd\u003eLow-voltage general purpose\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBC549\u003c\/td\u003e\n\u003ctd\u003e30V\u003c\/td\u003e\n\u003ctd\u003eVery low\u003c\/td\u003e\n\u003ctd\u003eLow-noise audio preamplifier\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eTypical Applications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSignal Switching:\u003c\/strong\u003e BC547 as a digital signal switch — drive relay coils, LEDs, buzzers, and small loads from Arduino and microcontroller GPIO pins (up to 100mA)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAudio Amplifier:\u003c\/strong\u003e BC547\/BC557 complementary pair in Class A and Class AB audio preamplifier stages for microphone, phono, and line-level signal amplification\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOscillator:\u003c\/strong\u003e BC547 in Colpitts, Hartley, and RC phase-shift oscillator circuits for signal generation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCurrent Mirror:\u003c\/strong\u003e BC547\/BC557 matched pair for precision current mirror circuits in analogue signal processing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePush-Pull Output Stage:\u003c\/strong\u003e BC547\/BC557 complementary emitter follower for low-power push-pull output stages in audio and signal circuits\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eArduino GPIO Expander:\u003c\/strong\u003e BC547 as a transistor switch to drive loads exceeding Arduino GPIO current limits (40mA max per pin)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eQ: What is the pinout of the BC547 and BC557 in TO-92 package?\u003c\/strong\u003e\u003cbr\u003eA: Holding the flat face of the TO-92 package towards you with the leads pointing down: Left = Collector (C), Centre = Base (B), Right = Emitter (E). Note: some manufacturers use CBE, others use EBC — verify against the datasheet for your specific batch.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQ: Can I use BC547\/BC557 to drive a relay directly from Arduino?\u003c\/strong\u003e\u003cbr\u003eA: Yes. Connect the Arduino GPIO pin through a 1kΩ base resistor to the BC547 base. Connect the relay coil between the collector and 5V\/12V supply. Add a flyback diode (1N4148) across the relay coil for inductive spike protection.\u003c\/p\u003e\n\u003ch3\u003ePackage Contents\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e50 × BC547B NPN transistor (TO-92)\u003c\/li\u003e\n\u003cli\u003e50 × BC557B PNP transistor (TO-92)\u003c\/li\u003e\n\u003cli\u003eTotal: 100pcs\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Keszoox","offers":[{"title":"Default Title","offer_id":46991477702891,"sku":"\u003cnone\u003e","price":8.08,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/1005\/8731\/files\/bc547-bc557-to92-npn-pnp-transistor-assorted-kit.webp?v=1761628982","url":"https:\/\/keszoox.com\/products\/bc547-bc557-to92-npn-pnp-transistor-assorted-kit-100pcs","provider":"Keszoox","version":"1.0","type":"link"}