2N4403

BC557B is an onsemi PNP general-purpose transistor — 45 V collector-emitter voltage, 100 mA continuous collector current, DC current gain of 200 to 450 (B rank) at 2 mA, 150 MHz transition frequency, TO-92 package, 500 mW dissipation, -55 to +150 °C. The B gain rank is the selection point: guaranteed 200-450 hFE for audio and general-purpose amplification where consistent gain matters, with NPN complements BC546/BC547 in the same family. Selection advice: the B suffix sets the gain rank — A is lower and C is higher, so match the full BC557B code to your gain requirement. Note the plain bulk TO-92 code is listed obsolete at some distributors while the BC557BTA/BC557BTF tape variants remain active — confirm the exact packing code when ordering. Evidence: onsemi/NXP BC557 datasheet and DigiKey listings confirm PNP, 45 V, 100 mA, hFE 200-450 and TO-92. Match the full BC557B code for gain rank. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

Diotec lists MMBT3906 as active — a PNP bipolar junction transistor, VCEO 40 V, IC 100 mA, 0.25 W, SOT-23 package, industrial grade. The MMBT3906 is the SMD incarnation of the classic 2N3906 and the complementary PNP to the MMBT3904: for push-pull, H-bridge or complementary amplifier stages, pair it with the MMBT3904 from the same manufacturer to keep characteristics matched. Selection advice: the through-hole 2N3906 is electrically equivalent but not footprint-compatible — match the MMBT3906 code to your SMD layout. Note the 100 mA collector rating, lower than the NPN sibling; verify your load current against it. Parameters verified against the Diotec official product page. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

MMBT3906LT1G is an onsemi general-purpose PNP transistor in SOT-23, tape and reel — the PNP complement to the MMBT3904LT1G on this site: high-side switching, push-pull stages and complementary pairs. 40 V, 200 mA with 250 MHz transition frequency is the selection point: the jellybean PNP that pairs with the 3904 for totem-pole and H-bridge drivers. Selection advice: the T1G suffix denotes tape and reel; order the 3904 and 3906 together when the design needs matched NPN/PNP pairs — they share footprint and qualification. AEC-Q101 qualified. hFE 300 minimum. Parameters verified against distributor and manufacturer documentation. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

2N3904 is the industry-standard NPN small-signal transistor — 40 V / 200 mA in TO-92 — for general-purpose amplification and switching: preamp stages, LED drivers, and logic-level interfacing. hFE spans 100–300 at 10 mA with a 300 MHz transition frequency, covering audio through low-VHF work. Selection advice: the complementary PNP is 2N3906 (same 40 V / 200 mA / TO-92) for push-pull and complementary driver stages. For SMD boards the direct equivalent is MMBT3904 in SOT-23 — the same die, already in this catalog. Diotec ships this part in ammo pack; if your line runs tape-and-reel, confirm the packing code on the quote. Do not confuse with the PN2222A: the 2N3904 tops out at 200 mA while the PN2222A handles 1 A — they share a footprint but not a current rating. Parameters trace to the manufacturer datasheet; state quantity, packing and date-code requirements in your RFQ — we reconfirm the offered lot before quotation and reply within 24 hours.

2N4401 is an onsemi NPN silicon general-purpose transistor — 40 V collector-emitter voltage, 600 mA continuous collector current, DC current gain of 100 minimum at 150 mA, 250 MHz transition frequency, TO-92 package, 625 mW dissipation, -55 to +150 °C. The complementary pairing is the selection point: the NPN counterpart of the 2N4403 PNP for push-pull, H-bridge and complementary switching stages. Selection advice: for a complementary pair order the 2N4403 (PNP) alongside this 2N4401 (NPN) — they share ratings for symmetric drive. The 625 mW dissipation limits continuous high-current use, so size the load or add a driver for power switching. Evidence: onsemi 2N4401 datasheet and distributor listings confirm NPN, 40 V, 600 mA, hFE 100, 250 MHz and TO-92. Match the full 2N4401 code. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

BC546B is an onsemi NPN general-purpose transistor — 65 V collector-emitter voltage, 100 mA continuous collector current, DC current gain of 200 to 450 (B rank), 300 MHz transition frequency, TO-92 package, 500 mW dissipation, -55 to +150 °C. The 65 V rating is the selection point: the highest-voltage grade of the BC54x family for high-voltage preamplifier stages and driver circuits. Selection advice: the B suffix sets the gain rank — A is lower and C is higher, so match the full BC546B code to your gain requirement. The PNP complement is the BC556B in the same family for push-pull stages. Evidence: onsemi/NXP BC54x datasheet and distributor listings confirm NPN, 65 V, 100 mA, hFE 200 to 450 (B rank) and TO-92. Match the full BC546B code for gain rank. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

BC547B is an onsemi NPN general-purpose transistor — 45 V collector-emitter voltage, 100 mA continuous collector current, DC current gain of 200 to 450 (B rank), 300 MHz transition frequency, TO-92 package, 500 mW dissipation, -55 to +150 °C. The 45 V rating with B gain rank is the selection point: the workhorse voltage grade of the BC54x family for general-purpose switching and amplification. Selection advice: the B suffix sets the gain rank — A is lower and C is higher, so match the full BC547B code to your gain requirement. The PNP complement is the BC557B in the same family for push-pull stages. Evidence: onsemi/NXP BC54x datasheet and distributor listings confirm NPN, 45 V, 100 mA, hFE 200 to 450 (B rank) and TO-92. Match the full BC547B code for gain rank. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

BC548B is an onsemi NPN general-purpose transistor — 30 V collector-emitter voltage, 100 mA continuous collector current, DC current gain of 200 to 450 (B rank), 300 MHz transition frequency, TO-92 package, 500 mW dissipation, -55 to +150 °C. The 30 V B-rank combination is the selection point: the low-voltage, mid-gain member of the BC54x family for audio driver stages and general amplification where 30 V headroom suffices. Selection advice: the B suffix sets the gain rank — A is lower and C is higher, so match the full BC548B code to your gain requirement. The PNP complement is the BC558B in the same family; for higher voltage use the BC546/BC547 grades. Evidence: onsemi/Fairchild BC548 datasheet and distributor listings confirm NPN, 30 V, 100 mA, hFE 200-450 and TO-92. Match the full BC548B code for gain rank. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

BC549C is an onsemi NPN low-noise general-purpose transistor — 30 V collector-emitter voltage, 100 mA continuous collector current, DC current gain of 420 to 800 (C rank), 300 MHz transition frequency, TO-92 package, 500 mW dissipation, -55 to +150 °C. The low-noise C rank is the selection point: 1.2-4 dB noise figure for audio preamplifier and low-noise input stages, with the highest gain rank of the family. Selection advice: the C suffix sets the gain rank — A is lower and B is middle, so match the full BC549C code to your gain requirement. The PNP complement is the BC559C in the same family. For higher voltage choose the BC546 family instead. Evidence: onsemi/NXP BC549 datasheet and distributor listings confirm NPN, 30 V, 100 mA, hFE 420-800 and TO-92. Match the full BC549C code for gain rank. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

1N4002 is a 1 A standard-recovery rectifier diode from the 1N400x family — 100 V repetitive peak reverse voltage, 1 A average forward current, 30 A surge capability, axial DO-41 (DO-204AL) package, 1.1 V maximum forward voltage, -65 to +150 °C. The 100 V rating is the selection point: the economical choice for low-voltage rectifiers, relay flyback clamps and reverse-polarity protection where high blocking voltage is unnecessary. Selection advice: pick the voltage grade to match your peak reverse voltage with margin — 1N4004 (400 V) or 1N4007 (1000 V) are the higher-voltage neighbors in the same DO-41 footprint. For switching supplies use an ultrafast type like UF5408 instead, since this is a standard-recovery part. Evidence: Vishay 1N4001–1N4007 datasheet confirms 1 A, 100 V, 30 A surge, DO-41 and 1.1 V forward voltage. Match the full 1N4002 code — the digit sets the voltage rating. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.