Part of the Day · 1N4148 — DO-35 small-signal switching diode

Part of the Day · 2026-10-23

A glass body with a single black band — the most common small-signal switching diode. With a fast 4ns reverse recovery time it is widely used for signal conditioning and protection.

Actual size

↓ Actual size, left edge aligned to 0 on the ruler

One ruler tick = 1mm. On PC this is actual size on a 24-inch FHD monitor at 100% zoom; on iPhone it adjusts automatically. For other screens, use “Calibrate ruler” below.

Enlarged (DO-35 · top view · approx. 15×)

Pins The end with the black band is the cathode (−)

leads partly shown · Package DO-35

Key specifications

Values are from the onsemi datasheet.

Marking and pins

Typical uses

• Logic / signal-line switching, signal rectification
• Absorbing back-EMF from relays and coils (low current)
• Input protection clamps, diode-OR circuits

Companion & similar parts

• 1N914 — Sibling part from the same datasheet — same VRRM, IO and trr, marked 914
• 1N4448 — Same family, forward voltage also guaranteed at 5mA and 100mA (marked 4448)
• FDLL4148 — Same die in an SMD glass package (SOD-80) — the wide black first band is the cathode

The glass body is usually marked 4148. For currents around 1A, use a rectifier diode such as the 1N4007 instead of the 1N4148.