Diode
1N4148
Small-signal fast-switching diode, DO-35 — 100V, 150mA average, 4ns reverse recovery.
1N4148 · Vishay Semiconductors
Overview
A general-purpose small-signal diode used for logic-level steering, clamping and protection, and as a flyback diode on genuinely small inductive loads (a reed relay, a tiny solenoid) — anywhere the current stays under ~150mA. Its defining feature next to a rectifier like the 1N4007 is speed: a 4ns reverse recovery time lets it switch cleanly at MHz-range frequencies, where a 1N4007 would still be conducting backwards. It is not a power part — asked to flyback a DC motor or a full-size relay coil, it will exceed its current rating and fail open or short.
Wiring tip: cathode (banded end) toward +V; anode toward the switched node
Pins & wiring
1N4148
DO-35
Logical order only — confirm the physical package drawing.
All pins
Hover · click to selectSelected pin
ANODE
- Direction
- Passive
Plain end of the glass body (no band).
Full pin table
| Name | Role | Direction | Note |
|---|---|---|---|
| Other | Passive | Plain end of the glass body (no band). | |
| Other | Passive | Marked by a black band on the glass body — this is the datasheet's positive-current-blocking end. |
Wiring examples
Flyback diode across a small (sub-100mA) relay or reed coil
Cathode to the coil's supply side, anode to the switched (transistor/MOSFET collector/drain) side — clamps the coil's turn-off voltage spike.
| 1N4148 pin | Connects to | Note |
|---|---|---|
| CATHODE | host Power (any matching pin) | To the coil's supply-side terminal (the + rail feeding the coil). |
| ANODE | BC547 · collector | To the switched side of the coil — the same node as the transistor's collector or MOSFET's drain. |
- Only good for coils drawing well under 150mA — use 1N4007 for a full-size relay or motor flyback.
Specifications
Footprint
No independently verified physical footprint is on file for this part yet.
Alternatives
Similar parts
Does the same job with a different part. Expect wiring and library changes — a starting point, not a guarantee.
People often ask whether one can substitute for the other — mostly not: 1N4007 is 6.5x the current rating but orders of magnitude slower to switch.
Compare with 1N4148- Avg forward current: 0.15A → 1.0A
- Reverse recovery: 4ns → not specified (slow) — 1N4007 is unsuitable for fast switching/PWM applications where 1N4148 excels.
Documents
Datasheets
- 1N4148 / 1N4148W Small Signal Fast Switching DiodesVishay Semiconductors
Frequently asked questions
What voltage does the 1N4148 run at?
Banana Board does not have a verified operating voltage on file for the 1N4148 yet — check the datasheet in Documents before wiring it up.
How many pins does the 1N4148 have?
The 1N4148 has 2 pins. See the full pinout table in Pins & wiring for each pin's role.
Can I simulate the 1N4148 before ordering hardware?
Not yet — the 1N4148 does not have a live simulation model in Banana Board today, so validate the wiring here and test on real hardware.
Where is the 1N4148 datasheet?
Linked in the Documents section on this page, and cited on every spec that came from it.
Related references
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