4N35

EL817(C) is an Everlight single-channel phototransistor optocoupler in 4-pin DIP — for galvanic isolation: SMPS feedback, PLC inputs and microcontroller isolation. 5000 Vrms isolation with 200–400 % CTR (C rank) is the selection point: the industry-standard PC817-compatible footprint. Selection advice: the (C) denotes the CTR rank — match the rank to your LED drive current and output load; the EL817 is pin-compatible with the PC817, giving a second source for supply resilience. For high-speed data isolation, digital isolators are the step up. Parameters verified against the Everlight official datasheet. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

1N4001 is an onsemi standard rectifier diode — VRRM 50 V, 1 A average rectified current, DO-41 axial package. The 1N400x family is the selection point: the cheapest diode on earth for mains-frequency rectification and reverse-polarity protection — a jellybean part every lab stocks by the thousand. Selection advice: the 1N4001 is the 50 V bottom grade of the 1N4001–1N4007 family (50 V to 1000 V, same DO-41 package) — for mains work always specify the 1N4007 (1000 V); the 1N4001 suits low-voltage rails only. For switching supplies above a few kHz use a fast-recovery type instead — standard recovery overheats at high frequency. onsemi lists the 1N4001 as Active. Evidence: distributor data confirms onsemi 1N4001 Active, 50 V, 1 A, DO-41. Match the full 1N4001 code — siblings look identical. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

1N4148 is the industry-standard high-speed switching diode — 100 V repetitive reverse voltage, 200 mA average forward current, 4 ns reverse recovery — in a DO-35 axial glass package. The 4 ns trr is the selection point: fast enough for megahertz switching, clamping and reverse-polarity steering in signal paths, where a 1N4007’s microsecond-scale recovery would distort or overheat. Selection advice: the bare 1N4148 code is the base part — onsemi ships it as 1N4148-T50A (ammo pack) or 1N4148-T50R (reel), so quote the suffixed code to get the right packing. For SMD boards the electrical equivalents are LL4148 (SOD-80) and 1N4148W (SOD-123), the same die in surface-mount packages. 1N914 is the older JEDEC number most vendors treat as interchangeable, but 1N4148’s leakage specification is tighter — stay with 1N4148 for precision clamping. Active through distribution. 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.

1N4733A is an onsemi 5.1 V Zener diode, 1 W maximum power dissipation, axial-lead DO-41 (DO-204AL) package — 5.1 V nominal Zener voltage at 49 mA test current, 7 Ω maximum Zener impedance, 10 µA maximum reverse leakage at 1 V, temperature coefficient −0.01 to +0.04 %/°C, color band marking the cathode. The 5.1 V value is the selection point: it is the natural shunt reference and overvoltage clamp for 5 V logic rails — a one-part overvoltage crowbar, reference or transient clamp where a precision IC reference would be overkill. Selection advice: the bare 1N4733A code is the general through-hole form; the -A suffix is ammo pack and -T is tape and reel — match the suffix to your insertion equipment. Note that only the -T50R variant is listed obsolete per PDN PD24582X; the exact code 1N4733A remains Active. onsemi lists 1N4733A as Active. Evidence: onsemi 1N4728A–1N4761A datasheet and distributor listings confirm 5.1 V, 1 W, 49 mA, DO-41 and Active status. Match the full 1N4733A code. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

onsemi lists 1N4742A as Active — a Zener diode, VZ typ 12 V at IZT 21 mA, P max 1 W, axial-lead DO-41 package. The 12 V Zener voltage is the selection point: a simple, robust shunt reference and overvoltage clamp for 12 V rails, gate protection and signal limiting. Selection advice: the 1N47xx family spans 3.3 V to 100 V in the same DO-41 package — a wrong-voltage sibling looks identical, so match the full 1N4742A code. Verify your bias current keeps the diode in breakdown within its 1 W dissipation limit. Parameters verified against the onsemi 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.

1N5817 is a JEDEC-registered Schottky rectifier diode — 20 V reverse voltage, 1 A average rectified current, forward drop maximum 0.45 V at 1 A, DO-41 axial package, −65 °C to +125 °C. The low forward drop is the selection point: roughly half the loss of a PN diode at 1 A — the default Schottky for reverse-polarity protection and low-voltage rectification. Selection advice: lifecycle note — onsemi lists its axial 1N5817 variants as Obsolete, but the 1N5817 is a multi-source JEDEC number; for ongoing production specify a current-production 1N5817 from an active manufacturer. Voltage-grade siblings 1N5818 (30 V) and 1N5819 (40 V) share the package — pick the grade that covers your rail with margin, since Schottky leakage rises with voltage and temperature. Evidence: onsemi/Vishay datasheets confirm 20 V, 1 A, 0.45 V VF, DO-41. Match the full order code on your BOM. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

2N2222A is an onsemi NPN silicon small-signal switching transistor — 40 V collector-emitter voltage, 600 mA continuous collector current, DC current gain of 100 to 300 at 150 mA, 250 MHz transition frequency, in TO-92, -55 to +150 °C. The high gain-bandwidth and fast switching are the selection point: the classic general-purpose NPN for signal amplification, fast switching and driver stages in commercial and industrial designs. Selection advice: the PNP complement is the 2N2907A for push-pull pairs; do not confuse the 2N2222 (30 V) with the 2N2222A (40 V) — the A suffix is the higher-voltage grade. The 625 mW dissipation limits continuous high-current use, so size the load or add a driver for power switching. Evidence: onsemi 2N2222A datasheet and distributor listings confirm 40 V, 600 mA, hFE 100-300, 250 MHz and TO-92. Match the full 2N2222A code — the A suffix matters for voltage rating. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

2N3906 is a JEDEC-registered PNP small-signal transistor in TO-92-3 — VCEO minimum 40 V, continuous collector current 0.2 A, hFE 100 to 300, transition frequency minimum 250 MHz, 625 mW dissipation, −55 °C to +150 °C junction. The 2N3906 is the selection point: the default PNP for small-signal switching and amplification — the complement to the 2N3904 NPN — stocked by every distributor for decades. Selection advice: lifecycle note — onsemi lists its 2N3906RLRAG TO-92 variant as Obsolete (last-time buy was 2012), but the 2N3906 is a multi-source JEDEC number; for ongoing production, specify a current-production 2N3906 from an active manufacturer and confirm the exact order code on the BOM rather than the bare JEDEC number. For switching duty check the 70 ns turn-on / 300 ns turn-off times against your frequency. Evidence: DigiKey and distributor data confirm onsemi 2N3906RLRAG Obsolete status and the 40 V / 0.2 A / 250 MHz parameters. Match the full order code on your BOM. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

2N5088 is an onsemi NPN low-noise amplifier transistor — 30 V collector-emitter voltage, 50 mA continuous collector current, DC current gain of 300 to 900, 50 MHz transition frequency, 625 mW dissipation, TO-92 package, -55 to +150 °C. The low-noise 300-900 gain range is the selection point: designed for low-level, low-noise preamplifier stages where the high minimum gain of 300 reduces base-current noise contribution. Selection advice: 2N5088 is the 30 V version — the 2N5089 is the 25 V version of the same family, so match the full 2N5088 code to your voltage requirement. Evidence: onsemi 2N5088/2N5089 datasheet and distributor listings confirm NPN, 30 V, 50 mA, hFE 300-900, 50 MHz and TO-92. Match the full 2N5088 code. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

2N5551 is an onsemi NPN general-purpose high-voltage amplifier transistor in TO-92 — 160 V collector-emitter breakdown, 180 V collector-base, 6 V emitter-base, 600 mA continuous collector current, 625 mW power dissipation, DC current gain 80 to 250, 100 MHz minimum transition frequency, −55 to +150 °C. The 160 V rating in a small-signal TO-92 is the selection point: high-voltage preamplifier stages, level shifters and gas-discharge display drivers get serious voltage headroom without moving to a power package. Selection advice: onsemi order codes carry the packing — 2N5551TA (ammo), 2N5551TFR (tape and reel), 2N5551BU (bulk) — match the suffix to your assembly line, and do not confuse it with the lower-voltage 2N3904. The MMBT5551 is the SOT-23 SMD equivalent for reflow designs. onsemi lists the bare 2N5551 code as Obsolete — treat any offer as end-of-life stock with date-code traceability. Evidence: onsemi 2N5551/MMBT5551 datasheet and distributor listings confirm 160 V, 600 mA, hFE 80–250, 100 MHz and TO-92. Match the full code. State quantity, packing and date-code requirements in your RFQ; we reconfirm the offered lot before quotation and reply within 24 hours.

4N35 is listed on the PC817 alternatives page as a functional candidate (registry model 4N35). Review that page’s checklist before substituting.

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