Reference sheet
Common diodes
1N4001, 1N4148, Schottky and zeners with their real limits
Common diodes
The band printed on the package marks the CATHODE — current flows into the unbanded end. Vf is the forward drop at typical current; reverse voltage is the maximum the diode blocks.
| Part | Type | Current | Reverse V | Vf | Notes |
|---|---|---|---|---|---|
| 1N4001…4007 | Rectifier | 1 A | 50…1000 V | ~0.7 V | The power-supply workhorse; 4007 (1000 V) covers everything |
| 1N5400…5408 | Rectifier | 3 A | 50…1000 V | ~0.8 V | The 1N400x, but beefier |
| 1N4148 | Small-signal | 200 mA | 100 V | ~0.7 V | Fast switching, the jellybean signal diode |
| 1N5817 / 5819 | Schottky | 1 A | 20 / 40 V | ~0.3 V | Low drop — reverse-polarity protection, OR-ing supplies |
| SS14 / SS34 | Schottky (SMD) | 1 / 3 A | 40 V | ~0.4 V | The SMA/SMC-package Schottky on most modules |
| BZX55 / BZX85 | Zener | 0.5 / 1.3 W | 2.4…75 V | — | Voltage reference / clamp; band still marks the cathode |
| 1N4728…4764 | Zener | 1 W | 3.3…100 V | — | The classic 1 W zener ladder |
| LEDs | Emitter | 2…20 mA | low (~5 V!) | 1.8…3.4 V | Long lead = anode; never reverse past ~5 V |
