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100PCS Common Diode Kit - 1N4148, 1N4007, 1N5819 & 1N5399 | ShillehTek Product Manual
Documentation / 100PCS Common Diode Kit - 1N4148, 1N4007, 1N5819 & 1N5399 | ShillehTek Product Manual

100PCS Common Diode Kit - 1N4148, 1N4007, 1N5819 & 1N5399 | ShillehTek Product Manual

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Overview

A 100-piece diode assortment covering the four most-essential general-purpose diodes: 1N4148 (signal switching), 1N4007 (1 A rectifier), 1N5819 (Schottky), and 1N5399 (1.5 A high-current rectifier). 25 of each in a labelled plastic bag — together they cover essentially every situation where you need a one-way current path: power-supply rectification, flyback / freewheeling protection on relays and motors, level-shifting, OR-gating two power supplies, low-loss reverse-polarity protection, and high-frequency signal switching.

All four are leaded through-hole DO-35 / DO-41 packages, the standard hobbyist form factor — they drop straight onto a breadboard, perfboard, or PCB pads. A black or coloured stripe / band marks the cathode (the negative end) on each diode — current flows into the anode and out of the cathode (opposite to the band).

This is the kit you reach for when you need a flyback diode for a relay, a rectifier for a 9V wall-wart power supply, a Schottky for a low-voltage-drop OR-gate, or just want to make sure a sensor's supply line can't be reverse-polarised by accident.

At a Glance

Total Pieces
100 (4 types × 25)
Types
1N4148, 1N4007, 1N5819, 1N5399
Package
DO-35 / DO-41 axial
Polarity
Cathode marked with a band
Voltage Range
100V (1N4148) – 1000V (1N4007)
Current Range
200 mA (1N4148) – 1.5 A (1N5399)

Per-Type Specifications

Part Type Max VR Max IF VF @ IF Best For
1N4148 Signal switching 100V 200 mA (avg) 1.0 V @ 10 mA Logic / signal switching, fast transitions, RF
1N4007 General rectifier 1000V 1 A (avg) 1.1 V @ 1 A 50/60 Hz mains-rectifier full-wave bridges, power supplies
1N5819 Schottky rectifier 40V 1 A (avg) 0.34 V @ 1 A Low-voltage drop OR-gating, reverse-polarity protection, power harvesting
1N5399 High-current rectifier 1000V 1.5 A (avg) 1.0 V @ 1.5 A Higher-current power supplies, motor / solenoid flyback

Common Use Cases

Snubbing the Inductive Kick from a Relay or Motor

When a relay coil de-energises, the collapsing magnetic field induces a large negative voltage spike across the coil — easily 100V or more. Without a flyback diode, this spike can destroy a transistor or microcontroller pin. Wire a diode across the coil with the cathode facing +V (so it's normally reverse-biased), and the spike is harmlessly clamped through the diode.

Signal Voltage / Current Recommended Diode
5V / 12V relay or small motor (< 500 mA) 1N4007 (cheap, tough, plenty of margin)
Larger 12V motor or solenoid (~1 A) 1N5399 (1.5 A, slightly more headroom)
Fast-switching relay (PWM coils, > 1 kHz) 1N5819 (Schottky — fast recovery time)

Reverse-Polarity Protection

If your circuit has a barrel-jack DC input and someone plugs in a wall-wart with the wrong polarity, the diode in series will block reverse current — nothing dies. The cost is a forward voltage drop on the supply.

Diode Voltage Drop @ 1 A Best Use
1N4007 / 1N5399 ~1 V Wall-wart input where 1V drop is acceptable
1N5819 (Schottky) ~0.34 V Battery-powered devices where every 100 mV matters; low-dropout regulators

Building a Bridge Rectifier from Discrete Diodes

A full-wave bridge from 4 diodes converts 9V AC (from a transformer) into pulsing DC. Add a smoothing capacitor on the output for a usable DC supply.

Component Value / Pick
4 × bridge diodes 1N4007 (1A) or 1N5399 (1.5A)
Smoothing capacitor 1000 µF or larger electrolytic, rated > peak voltage
Optional 7805 regulator For clean 5V output
Mains Warning: Building anything that connects to mains voltage (110V or 240V) is dangerous. Always use a transformer to step down to a safe SELV voltage before rectifying. Never wire mains directly to your bridge.

Reading a Diode

Each diode has two key markings:

Marking Meaning
Part number printed on body e.g., "1N4148" or "1N5819"
Coloured band / stripe at one end Cathode (negative). Current flows from anode → cathode (i.e., into the unbanded end and out the banded end).
Quick test: Use a multimeter on diode-test mode. Probe red on anode (unbanded) and black on cathode (banded): the meter should read ~0.6V for silicon diodes (1N4148, 1N4007, 1N5399) or ~0.3V for the Schottky (1N5819). Reverse the probes: should read OL (open). If both directions read OL, the diode is broken open. If both read low, it's shorted.

Frequently Asked Questions

Why does my diode get hot?
It's dissipating power: P = I × VF. A 1N4007 conducting 1 A at 1V drop = 1 W — easily warm. Above the rated current it overheats and fails. For higher currents either use a bigger diode (1N5408 = 3A) or a Schottky (lower VF = less heat).
Is the 1N4148 fast enough for switching at 1 MHz?
Yes — the 1N4148 has a reverse-recovery time of ~4 ns, which is fine for tens of MHz signal switching. For RF or fast power-converter work the 1N5819 Schottky is even faster (~minimal reverse recovery). The 1N4007 is much slower (~30 µs) and only suited to low-frequency power rectification, not signal work.
Can I use a 1N4007 in place of a 1N4148?
For low-frequency signal switching, yes — but it's slower and has a higher VF. For high-speed signals (above ~1 kHz) use the 1N4148. For DC steady-state rectification either works.
What is "Schottky" and why does it matter?
A Schottky diode uses a metal-semiconductor junction instead of two semiconductors. This gives it a much lower forward voltage (0.3-0.4V vs 0.6-0.7V for silicon) and faster recovery time. Tradeoff: slightly lower reverse-voltage rating (40V for 1N5819 vs 1000V for 1N4007). Use Schottky where every milliamp / millivolt matters or speed is critical.
My multimeter on diode mode reads "OL" both directions. Is the diode bad?
Yes — that's an open diode (failed broken). Replace it. The other failure mode is a short (reads low both directions). For a working diode you should see ~0.6V forward, OL reverse.
Do diodes have polarity? I think I've installed mine backwards.
Yes — very much so. The cathode (banded end) goes to the positive side in a freewheel/flyback configuration; in a series rectifier or polarity-protection diode the cathode goes to the load and the anode to the source. Reverse-installed diodes either don't conduct (load doesn't work) or conduct in the wrong direction (causes shorts or dead pins). Always verify by reading the band before powering up.