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Understand the 1N4148 diode: operation, common uses, datasheet specs, and practical circuit examples for SA makers, students, and engineers. Selection, troubleshooting, and local availability at Communica.
Key properties and most popular circuit uses for the 1N4148.
How to pick and calculate for fast switching, voltage, and current ratings.
Avoid common mistakes and find SA stock and brand options at Communica.
The 1N4148 rectifier diode is a silicon switching diode widely used for fast signal processing, circuit protection, and digital logic. Small, versatile, and affordable, it has become a standard in hobbyist kits and professional designs across South Africa. Whether you're learning basic electronics, building a prototype, or maintaining equipment, the 1N4148 is a reliable choice when you require quick response and low leakage.
| Parameter | Typical Value | Note |
|---|---|---|
| Maximum repetitive reverse voltage (VRRM) | 100V | Suitable for most low-voltage circuits |
| Average forward current (IF) | 300mA | Peak surge to 1A (short duration) |
| Reverse recovery time | ~4ns | Good for fast switching |
| Forward voltage (VF) | 0.7V @ 10mA | Typical silicon diode drop |
| Package | DO-35 (axial, glass) | Easy to breadboard or solder |
The 1N4148 is polarised: install with the stripe (cathode) in the right direction. Schematic symbol and physical pinout:
Anode ----|<|---- Cathode
|
Stripe (mark this end!)
Unlike power rectifier diodes (like the 1N4007), the 1N4148 is optimised for fast transitions, making it excellent for:
This speed (reverse recovery time < 4ns) is why you'll often see the 1N4148 in oscillator, clock, and switching circuits in school and university labs, as well as in industry test jigs and legacy panels found across South Africa.
Check these when picking a diode:
When switching a relay from a microcontroller (e.g., an Arduino or Raspberry Pi GPIO), always place a 1N4148 across the relay coil to protect your switch or transistor.
+5V ----[Relay Coil]-----+----
|
|<| 1N4148
|
|
GND
The cathode (stripe) connects to +5V, the anode to GND. This clamps voltage spikes when the relay switches off.
To bring down noisy logic or convert a negative-going signal to unipolar for microcontroller ADC measurement:
Signal In --|<|-----> Out (to ADC)
1N4148
Use Ohm's Law (V = I x R) to size current-limiting resistors if the diode carries current directly.
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I got the most pleasant service from Sydney and Windie
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Verified customerCommunica supplies semiconductors and electronic components to industries such as automotive, electrical, automation, mining, and education.
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