LED
5 mm red · Vf ≈ 1.9 V @ 20 mA
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Typical part: 5 mm through-hole LED
Ratings and limits
| Forward current | 20 mA continuous, 30 mA max |
|---|---|
| Reverse voltage | 5 V |
| V_F | red ~1.9 V, green ~2.1 V, blue/white ~3.0 V |
How to use it
Indicator. Always in series with a resistor: R = (V_supply − V_F) / I_F. The longer leg is the anode (+).
Lessons and builds that use it
- 555 astable (LED flasher)
- 555 monostable (one-shot timer)
- LED and its series resistor
- Comparator with a light sensor
- Blink: your first sketch
- Analog in, PWM out
- Light sensor with an ESP32
- Astable multivibrator (two transistors)
- LED constant-current driver
- 18650 battery level indicator (build)
- Automatic emergency light (build)
- Solar garden light with dusk switch (build)
- Water-level indicator (build)
- Perfboard: make every connection yourself